diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 73856ba..47876a4 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -81,44 +81,21 @@
     if: needs.ci-config.outputs.enabled == 'yes'
     runs-on: windows-latest
     steps:
-    - uses: actions/checkout@v1
-    - name: download git-sdk-64-minimal
-      shell: bash
-      run: |
-        ## Get artifact
-        urlbase=https://dev.azure.com/git-for-windows/git/_apis/build/builds
-        id=$(curl "$urlbase?definitions=22&statusFilter=completed&resultFilter=succeeded&\$top=1" |
-          jq -r ".value[] | .id")
-        download_url="$(curl "$urlbase/$id/artifacts" |
-          jq -r '.value[] | select(.name == "git-sdk-64-minimal").resource.downloadUrl')"
-        curl --connect-timeout 10 --retry 5 --retry-delay 0 --retry-max-time 240 \
-          -o artifacts.zip "$download_url"
-
-        ## Unzip and remove the artifact
-        unzip artifacts.zip
-        rm artifacts.zip
+    - uses: actions/checkout@v2
+    - uses: git-for-windows/setup-git-for-windows-sdk@v1
     - name: build
-      shell: powershell
+      shell: bash
       env:
         HOME: ${{runner.workspace}}
-        MSYSTEM: MINGW64
         NO_PERL: 1
-      run: |
-        & .\git-sdk-64-minimal\usr\bin\bash.exe -lc @"
-        printf '%s\n' /git-sdk-64-minimal/ >>.git/info/exclude
-
-          ci/make-test-artifacts.sh artifacts
-        "@
-    - name: upload build artifacts
-      uses: actions/upload-artifact@v1
+      run: ci/make-test-artifacts.sh artifacts
+    - name: zip up tracked files
+      run: git archive -o artifacts/tracked.tar.gz HEAD
+    - name: upload tracked files and build artifacts
+      uses: actions/upload-artifact@v2
       with:
         name: windows-artifacts
         path: artifacts
-    - name: upload git-sdk-64-minimal
-      uses: actions/upload-artifact@v1
-      with:
-        name: git-sdk-64-minimal
-        path: git-sdk-64-minimal
   windows-test:
     runs-on: windows-latest
     needs: [windows-build]
@@ -127,37 +104,25 @@
       matrix:
         nr: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
     steps:
-    - uses: actions/checkout@v1
-    - name: download build artifacts
-      uses: actions/download-artifact@v1
+    - name: download tracked files and build artifacts
+      uses: actions/download-artifact@v2
       with:
         name: windows-artifacts
         path: ${{github.workspace}}
-    - name: extract build artifacts
+    - name: extract tracked files and build artifacts
       shell: bash
-      run: tar xf artifacts.tar.gz
-    - name: download git-sdk-64-minimal
-      uses: actions/download-artifact@v1
-      with:
-        name: git-sdk-64-minimal
-        path: ${{github.workspace}}/git-sdk-64-minimal/
+      run: tar xf artifacts.tar.gz && tar xf tracked.tar.gz
+    - uses: git-for-windows/setup-git-for-windows-sdk@v1
     - name: test
-      shell: powershell
-      run: |
-        & .\git-sdk-64-minimal\usr\bin\bash.exe -lc @"
-          # Let Git ignore the SDK
-          printf '%s\n' /git-sdk-64-minimal/ >>.git/info/exclude
-
-          ci/run-test-slice.sh ${{matrix.nr}} 10
-        "@
+      shell: bash
+      run: ci/run-test-slice.sh ${{matrix.nr}} 10
     - name: ci/print-test-failures.sh
       if: failure()
-      shell: powershell
-      run: |
-        & .\git-sdk-64-minimal\usr\bin\bash.exe -lc ci/print-test-failures.sh
+      shell: bash
+      run: ci/print-test-failures.sh
     - name: Upload failed tests' directories
       if: failure() && env.FAILED_TEST_ARTIFACTS != ''
-      uses: actions/upload-artifact@v1
+      uses: actions/upload-artifact@v2
       with:
         name: failed-tests-windows
         path: ${{env.FAILED_TEST_ARTIFACTS}}
@@ -165,27 +130,12 @@
     needs: ci-config
     if: needs.ci-config.outputs.enabled == 'yes'
     env:
-      MSYSTEM: MINGW64
       NO_PERL: 1
       GIT_CONFIG_PARAMETERS: "'user.name=CI' 'user.email=ci@git'"
     runs-on: windows-latest
     steps:
-    - uses: actions/checkout@v1
-    - name: download git-sdk-64-minimal
-      shell: bash
-      run: |
-        ## Get artifact
-        urlbase=https://dev.azure.com/git-for-windows/git/_apis/build/builds
-        id=$(curl "$urlbase?definitions=22&statusFilter=completed&resultFilter=succeeded&\$top=1" |
-          jq -r ".value[] | .id")
-        download_url="$(curl "$urlbase/$id/artifacts" |
-          jq -r '.value[] | select(.name == "git-sdk-64-minimal").resource.downloadUrl')"
-        curl --connect-timeout 10 --retry 5 --retry-delay 0 --retry-max-time 240 \
-          -o artifacts.zip "$download_url"
-
-        ## Unzip and remove the artifact
-        unzip artifacts.zip
-        rm artifacts.zip
+    - uses: actions/checkout@v2
+    - uses: git-for-windows/setup-git-for-windows-sdk@v1
     - name: initialize vcpkg
       uses: actions/checkout@v2
       with:
@@ -203,75 +153,60 @@
     - name: add msbuild to PATH
       uses: microsoft/setup-msbuild@v1
     - name: copy dlls to root
-      shell: powershell
-      run: |
-        & compat\vcbuild\vcpkg_copy_dlls.bat release
-        if (!$?) { exit(1) }
+      shell: cmd
+      run: compat\vcbuild\vcpkg_copy_dlls.bat release
     - name: generate Visual Studio solution
       shell: bash
       run: |
         cmake `pwd`/contrib/buildsystems/ -DCMAKE_PREFIX_PATH=`pwd`/compat/vcbuild/vcpkg/installed/x64-windows \
-        -DMSGFMT_EXE=`pwd`/git-sdk-64-minimal/mingw64/bin/msgfmt.exe -DPERL_TESTS=OFF -DPYTHON_TESTS=OFF -DCURL_NO_CURL_CMAKE=ON
+        -DNO_GETTEXT=YesPlease -DPERL_TESTS=OFF -DPYTHON_TESTS=OFF -DCURL_NO_CURL_CMAKE=ON
     - name: MSBuild
       run: msbuild git.sln -property:Configuration=Release -property:Platform=x64 -maxCpuCount:4 -property:PlatformToolset=v142
     - name: bundle artifact tar
-      shell: powershell
+      shell: bash
       env:
         MSVC: 1
         VCPKG_ROOT: ${{github.workspace}}\compat\vcbuild\vcpkg
       run: |
-        & git-sdk-64-minimal\usr\bin\bash.exe -lc @"
-          mkdir -p artifacts &&
-          eval \"`$(make -n artifacts-tar INCLUDE_DLLS_IN_ARTIFACTS=YesPlease ARTIFACTS_DIRECTORY=artifacts 2>&1 | grep ^tar)\"
-        "@
-    - name: upload build artifacts
-      uses: actions/upload-artifact@v1
+        mkdir -p artifacts &&
+        eval "$(make -n artifacts-tar INCLUDE_DLLS_IN_ARTIFACTS=YesPlease ARTIFACTS_DIRECTORY=artifacts NO_GETTEXT=YesPlease 2>&1 | grep ^tar)"
+    - name: zip up tracked files
+      run: git archive -o artifacts/tracked.tar.gz HEAD
+    - name: upload tracked files and build artifacts
+      uses: actions/upload-artifact@v2
       with:
         name: vs-artifacts
         path: artifacts
   vs-test:
     runs-on: windows-latest
-    needs: [vs-build, windows-build]
+    needs: vs-build
     strategy:
       fail-fast: false
       matrix:
         nr: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
     steps:
-    - uses: actions/checkout@v1
-    - name: download git-sdk-64-minimal
-      uses: actions/download-artifact@v1
-      with:
-        name: git-sdk-64-minimal
-        path: ${{github.workspace}}/git-sdk-64-minimal/
-    - name: download build artifacts
-      uses: actions/download-artifact@v1
+    - uses: git-for-windows/setup-git-for-windows-sdk@v1
+    - name: download tracked files and build artifacts
+      uses: actions/download-artifact@v2
       with:
         name: vs-artifacts
         path: ${{github.workspace}}
-    - name: extract build artifacts
+    - name: extract tracked files and build artifacts
       shell: bash
-      run: tar xf artifacts.tar.gz
+      run: tar xf artifacts.tar.gz && tar xf tracked.tar.gz
     - name: test
-      shell: powershell
+      shell: bash
       env:
-        MSYSTEM: MINGW64
         NO_SVN_TESTS: 1
         GIT_TEST_SKIP_REBASE_P: 1
-      run: |
-        & .\git-sdk-64-minimal\usr\bin\bash.exe -lc @"
-          # Let Git ignore the SDK and the test-cache
-          printf '%s\n' /git-sdk-64-minimal/ /test-cache/ >>.git/info/exclude
-
-          ci/run-test-slice.sh ${{matrix.nr}} 10
-        "@
+      run: ci/run-test-slice.sh ${{matrix.nr}} 10
     - name: ci/print-test-failures.sh
       if: failure()
-      shell: powershell
-      run: |
-        & .\git-sdk-64-minimal\usr\bin\bash.exe -lc ci/print-test-failures.sh
+      shell: bash
+      run: ci/print-test-failures.sh
     - name: Upload failed tests' directories
       if: failure() && env.FAILED_TEST_ARTIFACTS != ''
-      uses: actions/upload-artifact@v1
+      uses: actions/upload-artifact@v2
       with:
         name: failed-tests-windows
         path: ${{env.FAILED_TEST_ARTIFACTS}}
@@ -302,14 +237,14 @@
       jobname: ${{matrix.vector.jobname}}
     runs-on: ${{matrix.vector.pool}}
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2
     - run: ci/install-dependencies.sh
     - run: ci/run-build-and-tests.sh
     - run: ci/print-test-failures.sh
       if: failure()
     - name: Upload failed tests' directories
       if: failure() && env.FAILED_TEST_ARTIFACTS != ''
-      uses: actions/upload-artifact@v1
+      uses: actions/upload-artifact@v2
       with:
         name: failed-tests-${{matrix.vector.jobname}}
         path: ${{env.FAILED_TEST_ARTIFACTS}}
@@ -336,7 +271,7 @@
       if: failure()
     - name: Upload failed tests' directories
       if: failure() && env.FAILED_TEST_ARTIFACTS != ''
-      uses: actions/upload-artifact@v1
+      uses: actions/upload-artifact@v2
       with:
         name: failed-tests-${{matrix.vector.jobname}}
         path: ${{env.FAILED_TEST_ARTIFACTS}}
@@ -347,9 +282,29 @@
       jobname: StaticAnalysis
     runs-on: ubuntu-18.04
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2
     - run: ci/install-dependencies.sh
     - run: ci/run-static-analysis.sh
+  sparse:
+    needs: ci-config
+    if: needs.ci-config.outputs.enabled == 'yes'
+    env:
+      jobname: sparse
+    runs-on: ubuntu-20.04
+    steps:
+    - name: Download a current `sparse` package
+      # Ubuntu's `sparse` version is too old for us
+      uses: git-for-windows/get-azure-pipelines-artifact@v0
+      with:
+        repository: git/git
+        definitionId: 10
+        artifact: sparse-20.04
+    - name: Install the current `sparse` package
+      run: sudo dpkg -i sparse-20.04/sparse_*.deb
+    - uses: actions/checkout@v2
+    - name: Install other dependencies
+      run: ci/install-dependencies.sh
+    - run: make sparse
   documentation:
     needs: ci-config
     if: needs.ci-config.outputs.enabled == 'yes'
@@ -357,6 +312,6 @@
       jobname: Documentation
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2
     - run: ci/install-dependencies.sh
     - run: ci/test-documentation.sh
diff --git a/Documentation/CodingGuidelines b/Documentation/CodingGuidelines
index e3af089..711cb91 100644
--- a/Documentation/CodingGuidelines
+++ b/Documentation/CodingGuidelines
@@ -551,6 +551,51 @@
  documentation, please see the documentation-related advice in the
  Documentation/SubmittingPatches file).
 
+ In order to ensure the documentation is inclusive, avoid assuming
+ that an unspecified example person is male or female, and think
+ twice before using "he", "him", "she", or "her".  Here are some
+ tips to avoid use of gendered pronouns:
+
+  - Prefer succinctness and matter-of-factly describing functionality
+    in the abstract.  E.g.
+
+     --short:: Emit output in the short-format.
+
+    and avoid something like these overly verbose alternatives:
+
+     --short:: Use this to emit output in the short-format.
+     --short:: You can use this to get output in the short-format.
+     --short:: A user who prefers shorter output could....
+     --short:: Should a person and/or program want shorter output, he
+               she/they/it can...
+
+    This practice often eliminates the need to involve human actors in
+    your description, but it is a good practice regardless of the
+    avoidance of gendered pronouns.
+
+  - When it becomes awkward to stick to this style, prefer "you" when
+    addressing the the hypothetical user, and possibly "we" when
+    discussing how the program might react to the user.  E.g.
+
+      You can use this option instead of --xyz, but we might remove
+      support for it in future versions.
+
+    while keeping in mind that you can probably be less verbose, e.g.
+
+      Use this instead of --xyz. This option might be removed in future
+      versions.
+
+  - If you still need to refer to an example person that is
+    third-person singular, you may resort to "singular they" to avoid
+    "he/she/him/her", e.g.
+
+      A contributor asks their upstream to pull from them.
+
+    Note that this sounds ungrammatical and unnatural to those who
+    learned that "they" is only used for third-person plural, e.g.
+    those who learn English as a second language in some parts of the
+    world.
+
  Every user-visible change should be reflected in the documentation.
  The same general rule as for code applies -- imitate the existing
  conventions.
diff --git a/Documentation/RelNotes/2.33.0.txt b/Documentation/RelNotes/2.33.0.txt
index d1e9276..a69531c 100644
--- a/Documentation/RelNotes/2.33.0.txt
+++ b/Documentation/RelNotes/2.33.0.txt
@@ -30,6 +30,9 @@
 
  * The userdiff pattern for C# learned the token "record".
 
+ * "git rev-list" learns to omit the "commit <object-name>" header
+   lines from the output with the `--no-commit-header` option.
+
 
 Performance, Internal Implementation, Development Support etc.
 
@@ -50,6 +53,15 @@
  * The backend for "diff -G/-S" has been updated to use pcre2 engine
    when available.
 
+ * Use ".DELETE_ON_ERROR" pseudo target to simplify our Makefile.
+
+ * Code cleanup around struct_type_init() functions.
+
+ * "git send-email" optimization.
+
+ * GitHub Actions / CI update.
+   (merge 0dc787a9f2 js/ci-windows-update later to maint).
+
 
 Fixes since v2.32
 -----------------
@@ -151,6 +163,26 @@
    but instead segfaulted, which has been corrected.
    (merge fe7fe62d8d rs/grep-parser-fix later to maint).
 
+ * The merge code had funny interactions between content based rename
+   detection and directory rename detection.
+   (merge 3585d0ea23 en/merge-dir-rename-corner-case-fix later to maint).
+
+ * When rebuilding the multi-pack index file reusing an existing one,
+   we used to blindly trust the existing file and ended up carrying
+   corrupted data into the updated file, which has been corrected.
+   (merge f89ecf7988 tb/midx-use-checksum later to maint).
+
+ * Update the location of system-side configuration file on Windows.
+   (merge e355307692 js/gfw-system-config-loc-fix later to maint).
+
+ * Code recently added to support common ancestry negotiation during
+   "git push" did not sanity check its arguments carefully enough.
+   (merge eff40457a4 ab/fetch-negotiate-segv-fix later to maint).
+
+ * Update the documentation not to assume users are of certain gender
+   and adds to guidelines to do so.
+   (merge 46a237f42f ds/gender-neutral-doc later to maint).
+
  * Other code cleanup, docfix, build fix, etc.
    (merge bfe35a6165 ah/doc-describe later to maint).
    (merge f302c1e4aa jc/clarify-revision-range later to maint).
@@ -179,3 +211,10 @@
    (merge ce24797d38 mr/cmake later to maint).
    (merge 9eb542f2ee ab/pre-auto-gc-hook-test later to maint).
    (merge 9fffc38583 bk/doc-commit-typofix later to maint).
+   (merge 1cf823d8f0 ks/submodule-cleanup later to maint).
+   (merge ebbf5d2b70 js/config-mak-windows-pcre-fix later to maint).
+   (merge 617480d75b hn/refs-iterator-peel-returns-boolean later to maint).
+   (merge 6a24cc71ed ar/submodule-helper-include-cleanup later to maint).
+   (merge 5632e838f8 rs/khash-alloc-cleanup later to maint).
+   (merge b1d87fbaf1 jk/typofix later to maint).
+   (merge e04170697a ab/gitignore-discovery-doc later to maint).
diff --git a/Documentation/SubmittingPatches b/Documentation/SubmittingPatches
index 55287d7..3e215f4 100644
--- a/Documentation/SubmittingPatches
+++ b/Documentation/SubmittingPatches
@@ -373,9 +373,8 @@
 . `Acked-by:` says that the person who is more familiar with the area
   the patch attempts to modify liked the patch.
 . `Reviewed-by:`, unlike the other tags, can only be offered by the
-  reviewer and means that she is completely satisfied that the patch
-  is ready for application.  It is usually offered only after a
-  detailed review.
+  reviewers themselves when they are completely satisfied with the
+  patch after a detailed analysis.
 . `Tested-by:` is used to indicate that the person applied the patch
   and found it to have the desired effect.
 
diff --git a/Documentation/config/diff.txt b/Documentation/config/diff.txt
index 2d3331f..32f8483 100644
--- a/Documentation/config/diff.txt
+++ b/Documentation/config/diff.txt
@@ -118,9 +118,10 @@
 	relative to the top of the working tree.
 
 diff.renameLimit::
-	The number of files to consider when performing the copy/rename
-	detection; equivalent to the 'git diff' option `-l`. This setting
-	has no effect if rename detection is turned off.
+	The number of files to consider in the exhaustive portion of
+	copy/rename detection; equivalent to the 'git diff' option
+	`-l`.  If not set, the default value is currently 1000.  This
+	setting has no effect if rename detection is turned off.
 
 diff.renames::
 	Whether and how Git detects renames.  If set to "false",
diff --git a/Documentation/config/fetch.txt b/Documentation/config/fetch.txt
index 6af6f5e..63748c0 100644
--- a/Documentation/config/fetch.txt
+++ b/Documentation/config/fetch.txt
@@ -69,7 +69,8 @@
 	setting defaults to "skipping".
 	Unknown values will cause 'git fetch' to error out.
 +
-See also the `--negotiation-tip` option for linkgit:git-fetch[1].
+See also the `--negotiate-only` and `--negotiation-tip` options to
+linkgit:git-fetch[1].
 
 fetch.showForcedUpdates::
 	Set to false to enable `--no-show-forced-updates` in
diff --git a/Documentation/config/merge.txt b/Documentation/config/merge.txt
index 6b66c83..e27cc63 100644
--- a/Documentation/config/merge.txt
+++ b/Documentation/config/merge.txt
@@ -33,10 +33,12 @@
 include::fmt-merge-msg.txt[]
 
 merge.renameLimit::
-	The number of files to consider when performing rename detection
-	during a merge; if not specified, defaults to the value of
-	diff.renameLimit. This setting has no effect if rename detection
-	is turned off.
+	The number of files to consider in the exhaustive portion of
+	rename detection during a merge.  If not specified, defaults
+	to the value of diff.renameLimit.  If neither
+	merge.renameLimit nor diff.renameLimit are specified,
+	currently defaults to 7000.  This setting has no effect if
+	rename detection is turned off.
 
 merge.renames::
 	Whether Git detects renames.  If set to "false", rename detection
diff --git a/Documentation/config/sendemail.txt b/Documentation/config/sendemail.txt
index cbc5af4..50baa5d 100644
--- a/Documentation/config/sendemail.txt
+++ b/Documentation/config/sendemail.txt
@@ -8,9 +8,6 @@
 	See linkgit:git-send-email[1] for description.  Note that this
 	setting is not subject to the 'identity' mechanism.
 
-sendemail.smtpssl (deprecated)::
-	Deprecated alias for 'sendemail.smtpEncryption = ssl'.
-
 sendemail.smtpsslcertpath::
 	Path to ca-certificates (either a directory or a single file).
 	Set it to an empty string to disable certificate verification.
diff --git a/Documentation/diff-options.txt b/Documentation/diff-options.txt
index 32e6dee..0aebe83 100644
--- a/Documentation/diff-options.txt
+++ b/Documentation/diff-options.txt
@@ -588,11 +588,17 @@
 of a delete/create pair.
 
 -l<num>::
-	The `-M` and `-C` options require O(n^2) processing time where n
-	is the number of potential rename/copy targets.  This
-	option prevents rename/copy detection from running if
-	the number of rename/copy targets exceeds the specified
-	number.
+	The `-M` and `-C` options involve some preliminary steps that
+	can detect subsets of renames/copies cheaply, followed by an
+	exhaustive fallback portion that compares all remaining
+	unpaired destinations to all relevant sources.  (For renames,
+	only remaining unpaired sources are relevant; for copies, all
+	original sources are relevant.)  For N sources and
+	destinations, this exhaustive check is O(N^2).  This option
+	prevents the exhaustive portion of rename/copy detection from
+	running if the number of source/destination files involved
+	exceeds the specified number.  Defaults to diff.renameLimit.
+	Note that a value of 0 is treated as unlimited.
 
 ifndef::git-format-patch[]
 --diff-filter=[(A|C|D|M|R|T|U|X|B)...[*]]::
diff --git a/Documentation/fetch-options.txt b/Documentation/fetch-options.txt
index 9e7b4e1..e967ff1 100644
--- a/Documentation/fetch-options.txt
+++ b/Documentation/fetch-options.txt
@@ -62,8 +62,17 @@
 abbreviated) SHA-1 of a commit. Specifying a glob is equivalent to specifying
 this option multiple times, one for each matching ref name.
 +
-See also the `fetch.negotiationAlgorithm` configuration variable
-documented in linkgit:git-config[1].
+See also the `fetch.negotiationAlgorithm` and `push.negotiate`
+configuration variables documented in linkgit:git-config[1], and the
+`--negotiate-only` option below.
+
+--negotiate-only::
+	Do not fetch anything from the server, and instead print the
+	ancestors of the provided `--negotiation-tip=*` arguments,
+	which we have in common with the server.
++
+Internally this is used to implement the `push.negotiate` option, see
+linkgit:git-config[1].
 
 --dry-run::
 	Show what would be done, without making any changes.
diff --git a/Documentation/git-diff.txt b/Documentation/git-diff.txt
index 7f4c8a8..6236c75 100644
--- a/Documentation/git-diff.txt
+++ b/Documentation/git-diff.txt
@@ -51,16 +51,20 @@
 	--staged is a synonym of --cached.
 +
 If --merge-base is given, instead of using <commit>, use the merge base
-of <commit> and HEAD.  `git diff --merge-base A` is equivalent to
-`git diff $(git merge-base A HEAD)`.
+of <commit> and HEAD.  `git diff --cached --merge-base A` is equivalent to
+`git diff --cached $(git merge-base A HEAD)`.
 
-'git diff' [<options>] <commit> [--] [<path>...]::
+'git diff' [<options>] [--merge-base] <commit> [--] [<path>...]::
 
 	This form is to view the changes you have in your
 	working tree relative to the named <commit>.  You can
 	use HEAD to compare it with the latest commit, or a
 	branch name to compare with the tip of a different
 	branch.
++
+If --merge-base is given, instead of using <commit>, use the merge base
+of <commit> and HEAD.  `git diff --merge-base A` is equivalent to
+`git diff $(git merge-base A HEAD)`.
 
 'git diff' [<options>] [--merge-base] <commit> <commit> [--] [<path>...]::
 
diff --git a/Documentation/git-push.txt b/Documentation/git-push.txt
index a953c7c..2f25aa3 100644
--- a/Documentation/git-push.txt
+++ b/Documentation/git-push.txt
@@ -244,8 +244,8 @@
 You will have to bypass the "must fast-forward" rule in order to
 replace the history you originally published with the rebased history.
 If somebody else built on top of your original history while you are
-rebasing, the tip of the branch at the remote may advance with her
-commit, and blindly pushing with `--force` will lose her work.
+rebasing, the tip of the branch at the remote may advance with their
+commit, and blindly pushing with `--force` will lose their work.
 +
 This option allows you to say that you expect the history you are
 updating is what you rebased and want to replace. If the remote ref
diff --git a/Documentation/git-worktree.txt b/Documentation/git-worktree.txt
index 66e67e6..8a7cbdd 100644
--- a/Documentation/git-worktree.txt
+++ b/Documentation/git-worktree.txt
@@ -9,7 +9,7 @@
 SYNOPSIS
 --------
 [verse]
-'git worktree add' [-f] [--detach] [--checkout] [--lock] [-b <new-branch>] <path> [<commit-ish>]
+'git worktree add' [-f] [--detach] [--checkout] [--lock [--reason <string>]] [-b <new-branch>] <path> [<commit-ish>]
 'git worktree list' [--porcelain]
 'git worktree lock' [--reason <string>] <worktree>
 'git worktree move' <worktree> <new-path>
@@ -242,7 +242,7 @@
 older than `<time>`.
 
 --reason <string>::
-	With `lock`, an explanation why the working tree is locked.
+	With `lock` or with `add --lock`, an explanation why the working tree is locked.
 
 <worktree>::
 	Working trees can be identified by path, either relative or
diff --git a/Documentation/gitignore.txt b/Documentation/gitignore.txt
index 53e7d5c..f8a1fc2 100644
--- a/Documentation/gitignore.txt
+++ b/Documentation/gitignore.txt
@@ -27,12 +27,11 @@
    them.
 
  * Patterns read from a `.gitignore` file in the same directory
-   as the path, or in any parent directory, with patterns in the
-   higher level files (up to the toplevel of the work tree) being overridden
-   by those in lower level files down to the directory containing the file.
-   These patterns match relative to the location of the
-   `.gitignore` file.  A project normally includes such
-   `.gitignore` files in its repository, containing patterns for
+   as the path, or in any parent directory (up to the top-level of the working
+   tree), with patterns in the higher level files being overridden by those in
+   lower level files down to the directory containing the file. These patterns
+   match relative to the location of the `.gitignore` file.  A project normally
+   includes such `.gitignore` files in its repository, containing patterns for
    files generated as part of the project build.
 
  * Patterns read from `$GIT_DIR/info/exclude`.
diff --git a/Documentation/rev-list-options.txt b/Documentation/rev-list-options.txt
index 5bf2a85..24569b0 100644
--- a/Documentation/rev-list-options.txt
+++ b/Documentation/rev-list-options.txt
@@ -897,7 +897,7 @@
 +
 The form '--filter=sparse:oid=<blob-ish>' uses a sparse-checkout
 specification contained in the blob (or blob-expression) '<blob-ish>'
-to omit blobs that would not be not required for a sparse checkout on
+to omit blobs that would not be required for a sparse checkout on
 the requested refs.
 +
 The form '--filter=tree:<depth>' omits all blobs and trees whose depth
@@ -1064,6 +1064,14 @@
 --header::
 	Print the contents of the commit in raw-format; each record is
 	separated with a NUL character.
+
+--no-commit-header::
+	Suppress the header line containing "commit" and the object ID printed before
+	the specified format.  This has no effect on the built-in formats; only custom
+	formats are affected.
+
+--commit-header::
+	Overrides a previous `--no-commit-header`.
 endif::git-rev-list[]
 
 --parents::
diff --git a/Documentation/user-manual.txt b/Documentation/user-manual.txt
index f9e54b8..9624059 100644
--- a/Documentation/user-manual.txt
+++ b/Documentation/user-manual.txt
@@ -2792,7 +2792,7 @@
 
 In some cases it is possible that the new head will *not* actually be
 a descendant of the old head.  For example, the developer may have
-realized she made a serious mistake, and decided to backtrack,
+realized a serious mistake was made and decided to backtrack,
 resulting in a situation like:
 
 ................................................
diff --git a/Makefile b/Makefile
index 502e0c9..c6f6246 100644
--- a/Makefile
+++ b/Makefile
@@ -726,9 +726,11 @@
 TEST_BUILTINS_OBJS += test-mktemp.o
 TEST_BUILTINS_OBJS += test-oid-array.o
 TEST_BUILTINS_OBJS += test-oidmap.o
+TEST_BUILTINS_OBJS += test-oidtree.o
 TEST_BUILTINS_OBJS += test-online-cpus.o
 TEST_BUILTINS_OBJS += test-parse-options.o
 TEST_BUILTINS_OBJS += test-parse-pathspec-file.o
+TEST_BUILTINS_OBJS += test-partial-clone.o
 TEST_BUILTINS_OBJS += test-path-utils.o
 TEST_BUILTINS_OBJS += test-pcre2-config.o
 TEST_BUILTINS_OBJS += test-pkt-line.o
@@ -849,6 +851,7 @@
 LIB_OBJS += bulk-checkin.o
 LIB_OBJS += bundle.o
 LIB_OBJS += cache-tree.o
+LIB_OBJS += cbtree.o
 LIB_OBJS += chdir-notify.o
 LIB_OBJS += checkout.o
 LIB_OBJS += chunk-format.o
@@ -944,6 +947,7 @@
 LIB_OBJS += oid-array.o
 LIB_OBJS += oidmap.o
 LIB_OBJS += oidset.o
+LIB_OBJS += oidtree.o
 LIB_OBJS += pack-bitmap-write.o
 LIB_OBJS += pack-bitmap.o
 LIB_OBJS += pack-check.o
@@ -2164,6 +2168,16 @@
 strip: $(PROGRAMS) git$X
 	$(STRIP) $(STRIP_OPTS) $^
 
+### Flags affecting all rules
+
+# A GNU make extension since gmake 3.72 (released in late 1994) to
+# remove the target of rules if commands in those rules fail. The
+# default is to only do that if make itself receives a signal. Affects
+# all targets, see:
+#
+#    info make --index-search=.DELETE_ON_ERROR
+.DELETE_ON_ERROR:
+
 ### Target-specific flags and dependencies
 
 # The generic compilation pattern rule and automatically
@@ -2247,7 +2261,6 @@
 	$(gitwebdir_SQ):$(PERL_PATH_SQ):$(SANE_TEXT_GREP):$(PAGER_ENV):\
 	$(perllibdir_SQ)
 define cmd_munge_script
-$(RM) $@ $@+ && \
 sed -e '1s|#!.*/sh|#!$(SHELL_PATH_SQ)|' \
     -e 's|@SHELL_PATH@|$(SHELL_PATH_SQ)|' \
     -e 's|@@DIFF@@|$(DIFF_SQ)|' \
@@ -2317,7 +2330,7 @@
 PERL_DEFINES += $(gitexecdir) $(perllibdir) $(localedir)
 
 $(SCRIPT_PERL_GEN): % : %.perl GIT-PERL-DEFINES GIT-PERL-HEADER GIT-VERSION-FILE
-	$(QUIET_GEN)$(RM) $@ $@+ && \
+	$(QUIET_GEN) \
 	sed -e '1{' \
 	    -e '	s|#!.*perl|#!$(PERL_PATH_SQ)|' \
 	    -e '	r GIT-PERL-HEADER' \
@@ -2337,7 +2350,7 @@
 	    fi
 
 GIT-PERL-HEADER: $(PERL_HEADER_TEMPLATE) GIT-PERL-DEFINES Makefile
-	$(QUIET_GEN)$(RM) $@ && \
+	$(QUIET_GEN) \
 	INSTLIBDIR='$(perllibdir_SQ)' && \
 	INSTLIBDIR_EXTRA='$(PERLLIB_EXTRA_SQ)' && \
 	INSTLIBDIR="$$INSTLIBDIR$${INSTLIBDIR_EXTRA:+:$$INSTLIBDIR_EXTRA}" && \
@@ -2363,7 +2376,7 @@
 	mv $@+ $@
 else # NO_PERL
 $(SCRIPT_PERL_GEN) git-instaweb: % : unimplemented.sh
-	$(QUIET_GEN)$(RM) $@ $@+ && \
+	$(QUIET_GEN) \
 	sed -e '1s|#!.*/sh|#!$(SHELL_PATH_SQ)|' \
 	    -e 's|@@REASON@@|NO_PERL=$(NO_PERL)|g' \
 	    unimplemented.sh >$@+ && \
@@ -2377,14 +2390,14 @@
 ifndef NO_PYTHON
 $(SCRIPT_PYTHON_GEN): GIT-CFLAGS GIT-PREFIX GIT-PYTHON-VARS
 $(SCRIPT_PYTHON_GEN): % : %.py
-	$(QUIET_GEN)$(RM) $@ $@+ && \
+	$(QUIET_GEN) \
 	sed -e '1s|#!.*python|#!$(PYTHON_PATH_SQ)|' \
 	    $< >$@+ && \
 	chmod +x $@+ && \
 	mv $@+ $@
 else # NO_PYTHON
 $(SCRIPT_PYTHON_GEN): % : unimplemented.sh
-	$(QUIET_GEN)$(RM) $@ $@+ && \
+	$(QUIET_GEN) \
 	sed -e '1s|#!.*/sh|#!$(SHELL_PATH_SQ)|' \
 	    -e 's|@@REASON@@|NO_PYTHON=$(NO_PYTHON)|g' \
 	    unimplemented.sh >$@+ && \
@@ -2392,8 +2405,7 @@
 	mv $@+ $@
 endif # NO_PYTHON
 
-CONFIGURE_RECIPE = $(RM) configure configure.ac+ && \
-		   sed -e 's/@@GIT_VERSION@@/$(GIT_VERSION)/g' \
+CONFIGURE_RECIPE = sed -e 's/@@GIT_VERSION@@/$(GIT_VERSION)/g' \
 			configure.ac >configure.ac+ && \
 		   autoconf -o configure configure.ac+ && \
 		   $(RM) configure.ac+
@@ -2518,7 +2530,6 @@
 ifeq ($(GENERATE_COMPILATION_DATABASE),yes)
 all:: compile_commands.json
 compile_commands.json:
-	@$(RM) $@
 	$(QUIET_GEN)sed -e '1s/^/[/' -e '$$s/,$$/]/' $(compdb_dir)/*.o.json > $@+
 	@if test -s $@+; then mv $@+ $@; else $(RM) $@+; fi
 endif
@@ -2591,10 +2602,10 @@
 		$(CURL_LIBCURL) $(EXPAT_LIBEXPAT) $(LIBS)
 
 $(LIB_FILE): $(LIB_OBJS)
-	$(QUIET_AR)$(RM) $@ && $(AR) $(ARFLAGS) $@ $^
+	$(QUIET_AR)$(AR) $(ARFLAGS) $@ $^
 
 $(XDIFF_LIB): $(XDIFF_OBJS)
-	$(QUIET_AR)$(RM) $@ && $(AR) $(ARFLAGS) $@ $^
+	$(QUIET_AR)$(AR) $(ARFLAGS) $@ $^
 
 export DEFAULT_EDITOR DEFAULT_PAGER
 
@@ -2679,10 +2690,13 @@
 .PHONY: pot
 pot: po/git.pot
 
+ifdef NO_GETTEXT
+POFILES :=
+MOFILES :=
+else
 POFILES := $(wildcard po/*.po)
 MOFILES := $(patsubst po/%.po,po/build/locale/%/LC_MESSAGES/git.mo,$(POFILES))
 
-ifndef NO_GETTEXT
 all:: $(MOFILES)
 endif
 
diff --git a/add-patch.c b/add-patch.c
index 2fad92c..8c41cdf 100644
--- a/add-patch.c
+++ b/add-patch.c
@@ -280,6 +280,7 @@
 	clear_add_i_state(&s->s);
 }
 
+__attribute__((format (printf, 2, 3)))
 static void err(struct add_p_state *s, const char *fmt, ...)
 {
 	va_list args;
diff --git a/advice.h b/advice.h
index bd26c38..9f8ffc7 100644
--- a/advice.h
+++ b/advice.h
@@ -90,6 +90,7 @@
 /**
  * Checks the visibility of the advice before printing.
  */
+__attribute__((format (printf, 2, 3)))
 void advise_if_enabled(enum advice_type type, const char *advice, ...);
 
 int error_resolve_conflict(const char *me);
diff --git a/apply.c b/apply.c
index 853d3ed..44bc31d 100644
--- a/apply.c
+++ b/apply.c
@@ -101,9 +101,9 @@
 	state->ws_error_action = warn_on_ws_error;
 	state->ws_ignore_action = ignore_ws_none;
 	state->linenr = 1;
-	string_list_init(&state->fn_table, 0);
-	string_list_init(&state->limit_by_name, 0);
-	string_list_init(&state->symlink_changes, 0);
+	string_list_init_nodup(&state->fn_table);
+	string_list_init_nodup(&state->limit_by_name);
+	string_list_init_nodup(&state->symlink_changes);
 	strbuf_init(&state->root, 0);
 
 	git_apply_config();
diff --git a/archive.c b/archive.c
index ff2bb54..3c266d1 100644
--- a/archive.c
+++ b/archive.c
@@ -645,7 +645,7 @@
 	args.pretty_ctx = &ctx;
 	args.repo = repo;
 	args.prefix = prefix;
-	string_list_init(&args.extra_files, 1);
+	string_list_init_dup(&args.extra_files);
 	argc = parse_archive_args(argc, argv, &ar, &args, name_hint, remote);
 	if (!startup_info->have_repository) {
 		/*
diff --git a/builtin/add.c b/builtin/add.c
index b773b5a..09e6845 100644
--- a/builtin/add.c
+++ b/builtin/add.c
@@ -470,7 +470,7 @@
 {
 	int exit_status = 0;
 	struct pathspec pathspec;
-	struct dir_struct dir;
+	struct dir_struct dir = DIR_INIT;
 	int flags;
 	int add_new_files;
 	int require_pathspec;
@@ -577,7 +577,6 @@
 	die_in_unpopulated_submodule(&the_index, prefix);
 	die_path_inside_submodule(&the_index, &pathspec);
 
-	dir_init(&dir);
 	if (add_new_files) {
 		int baselen;
 
diff --git a/builtin/am.c b/builtin/am.c
index 0b2d886..0c2ad96 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -210,6 +210,7 @@
  * If state->quiet is false, calls fprintf(fp, fmt, ...), and appends a newline
  * at the end.
  */
+__attribute__((format (printf, 3, 4)))
 static void say(const struct am_state *state, FILE *fp, const char *fmt, ...)
 {
 	va_list ap;
diff --git a/builtin/bisect--helper.c b/builtin/bisect--helper.c
index 9d9540a..f184eae 100644
--- a/builtin/bisect--helper.c
+++ b/builtin/bisect--helper.c
@@ -117,6 +117,7 @@
 	return fclose(fp);
 }
 
+__attribute__((format (printf, 2, 3)))
 static int write_to_file(const char *path, const char *format, ...)
 {
 	int res;
@@ -129,6 +130,7 @@
 	return res;
 }
 
+__attribute__((format (printf, 2, 3)))
 static int append_to_file(const char *path, const char *format, ...)
 {
 	int res;
diff --git a/builtin/bundle.c b/builtin/bundle.c
index ea69481..053a51b 100644
--- a/builtin/bundle.c
+++ b/builtin/bundle.c
@@ -46,7 +46,7 @@
 		const char* prefix,
 		const char * const usagestr[],
 		const struct option options[],
-		const char **bundle_file) {
+		char **bundle_file) {
 	int newargc;
 	newargc = parse_options(argc, argv, NULL, options, usagestr,
 			     PARSE_OPT_STOP_AT_NON_OPTION);
@@ -61,7 +61,7 @@
 	int progress = isatty(STDERR_FILENO);
 	struct strvec pack_opts;
 	int version = -1;
-
+	int ret;
 	struct option options[] = {
 		OPT_SET_INT('q', "quiet", &progress,
 			    N_("do not show progress meter"), 0),
@@ -76,7 +76,7 @@
 			    N_("specify bundle format version")),
 		OPT_END()
 	};
-	const char* bundle_file;
+	char *bundle_file;
 
 	argc = parse_options_cmd_bundle(argc, argv, prefix,
 			builtin_bundle_create_usage, options, &bundle_file);
@@ -94,75 +94,95 @@
 
 	if (!startup_info->have_repository)
 		die(_("Need a repository to create a bundle."));
-	return !!create_bundle(the_repository, bundle_file, argc, argv, &pack_opts, version);
+	ret = !!create_bundle(the_repository, bundle_file, argc, argv, &pack_opts, version);
+	free(bundle_file);
+	return ret;
 }
 
 static int cmd_bundle_verify(int argc, const char **argv, const char *prefix) {
-	struct bundle_header header;
+	struct bundle_header header = BUNDLE_HEADER_INIT;
 	int bundle_fd = -1;
 	int quiet = 0;
-
+	int ret;
 	struct option options[] = {
 		OPT_BOOL('q', "quiet", &quiet,
 			    N_("do not show bundle details")),
 		OPT_END()
 	};
-	const char* bundle_file;
+	char *bundle_file;
 
 	argc = parse_options_cmd_bundle(argc, argv, prefix,
 			builtin_bundle_verify_usage, options, &bundle_file);
 	/* bundle internals use argv[1] as further parameters */
 
-	memset(&header, 0, sizeof(header));
-	if ((bundle_fd = read_bundle_header(bundle_file, &header)) < 0)
-		return 1;
+	if ((bundle_fd = read_bundle_header(bundle_file, &header)) < 0) {
+		ret = 1;
+		goto cleanup;
+	}
 	close(bundle_fd);
-	if (verify_bundle(the_repository, &header, !quiet))
-		return 1;
+	if (verify_bundle(the_repository, &header, !quiet)) {
+		ret = 1;
+		goto cleanup;
+	}
+
 	fprintf(stderr, _("%s is okay\n"), bundle_file);
-	return 0;
+	ret = 0;
+cleanup:
+	free(bundle_file);
+	bundle_header_release(&header);
+	return ret;
 }
 
 static int cmd_bundle_list_heads(int argc, const char **argv, const char *prefix) {
-	struct bundle_header header;
+	struct bundle_header header = BUNDLE_HEADER_INIT;
 	int bundle_fd = -1;
-
+	int ret;
 	struct option options[] = {
 		OPT_END()
 	};
-	const char* bundle_file;
+	char *bundle_file;
 
 	argc = parse_options_cmd_bundle(argc, argv, prefix,
 			builtin_bundle_list_heads_usage, options, &bundle_file);
 	/* bundle internals use argv[1] as further parameters */
 
-	memset(&header, 0, sizeof(header));
-	if ((bundle_fd = read_bundle_header(bundle_file, &header)) < 0)
-		return 1;
+	if ((bundle_fd = read_bundle_header(bundle_file, &header)) < 0) {
+		ret = 1;
+		goto cleanup;
+	}
 	close(bundle_fd);
-	return !!list_bundle_refs(&header, argc, argv);
+	ret = !!list_bundle_refs(&header, argc, argv);
+cleanup:
+	free(bundle_file);
+	bundle_header_release(&header);
+	return ret;
 }
 
 static int cmd_bundle_unbundle(int argc, const char **argv, const char *prefix) {
-	struct bundle_header header;
+	struct bundle_header header = BUNDLE_HEADER_INIT;
 	int bundle_fd = -1;
-
+	int ret;
 	struct option options[] = {
 		OPT_END()
 	};
-	const char* bundle_file;
+	char *bundle_file;
 
 	argc = parse_options_cmd_bundle(argc, argv, prefix,
 			builtin_bundle_unbundle_usage, options, &bundle_file);
 	/* bundle internals use argv[1] as further parameters */
 
-	memset(&header, 0, sizeof(header));
-	if ((bundle_fd = read_bundle_header(bundle_file, &header)) < 0)
-		return 1;
+	if ((bundle_fd = read_bundle_header(bundle_file, &header)) < 0) {
+		ret = 1;
+		goto cleanup;
+	}
 	if (!startup_info->have_repository)
 		die(_("Need a repository to unbundle."));
-	return !!unbundle(the_repository, &header, bundle_fd, 0) ||
+	ret = !!unbundle(the_repository, &header, bundle_fd, 0) ||
 		list_bundle_refs(&header, argc, argv);
+	bundle_header_release(&header);
+cleanup:
+	free(bundle_file);
+	return ret;
 }
 
 int cmd_bundle(int argc, const char **argv, const char *prefix)
diff --git a/builtin/check-ignore.c b/builtin/check-ignore.c
index 8123455..2191256 100644
--- a/builtin/check-ignore.c
+++ b/builtin/check-ignore.c
@@ -153,7 +153,7 @@
 int cmd_check_ignore(int argc, const char **argv, const char *prefix)
 {
 	int num_ignored;
-	struct dir_struct dir;
+	struct dir_struct dir = DIR_INIT;
 
 	git_config(git_default_config, NULL);
 
@@ -182,7 +182,6 @@
 	if (!no_index && read_cache() < 0)
 		die(_("index file corrupt"));
 
-	dir_init(&dir);
 	setup_standard_excludes(&dir);
 
 	if (stdin_paths) {
diff --git a/builtin/clean.c b/builtin/clean.c
index 4944cf44..98a2860 100644
--- a/builtin/clean.c
+++ b/builtin/clean.c
@@ -641,7 +641,7 @@
 
 static int filter_by_patterns_cmd(void)
 {
-	struct dir_struct dir;
+	struct dir_struct dir = DIR_INIT;
 	struct strbuf confirm = STRBUF_INIT;
 	struct strbuf **ignore_list;
 	struct string_list_item *item;
@@ -665,7 +665,6 @@
 		if (!confirm.len)
 			break;
 
-		dir_init(&dir);
 		pl = add_pattern_list(&dir, EXC_CMDL, "manual exclude");
 		ignore_list = strbuf_split_max(&confirm, ' ', 0);
 
@@ -890,7 +889,7 @@
 	int ignored_only = 0, config_set = 0, errors = 0, gone = 1;
 	int rm_flags = REMOVE_DIR_KEEP_NESTED_GIT;
 	struct strbuf abs_path = STRBUF_INIT;
-	struct dir_struct dir;
+	struct dir_struct dir = DIR_INIT;
 	struct pathspec pathspec;
 	struct strbuf buf = STRBUF_INIT;
 	struct string_list exclude_list = STRING_LIST_INIT_NODUP;
@@ -921,7 +920,6 @@
 	argc = parse_options(argc, argv, prefix, options, builtin_clean_usage,
 			     0);
 
-	dir_init(&dir);
 	if (!interactive && !dry_run && !force) {
 		if (config_set)
 			die(_("clean.requireForce set to true and neither -i, -n, nor -f given; "
diff --git a/builtin/commit.c b/builtin/commit.c
index 190d215..7436262 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -889,7 +889,22 @@
 		int ident_shown = 0;
 		int saved_color_setting;
 		struct ident_split ci, ai;
-
+		const char *hint_cleanup_all = allow_empty_message ?
+			_("Please enter the commit message for your changes."
+			  " Lines starting\nwith '%c' will be ignored.\n") :
+			_("Please enter the commit message for your changes."
+			  " Lines starting\nwith '%c' will be ignored, and an empty"
+			  " message aborts the commit.\n");
+		const char *hint_cleanup_space = allow_empty_message ?
+			_("Please enter the commit message for your changes."
+			  " Lines starting\n"
+			  "with '%c' will be kept; you may remove them"
+			  " yourself if you want to.\n") :
+			_("Please enter the commit message for your changes."
+			  " Lines starting\n"
+			  "with '%c' will be kept; you may remove them"
+			  " yourself if you want to.\n"
+			  "An empty message aborts the commit.\n");
 		if (whence != FROM_COMMIT) {
 			if (cleanup_mode == COMMIT_MSG_CLEANUP_SCISSORS &&
 				!merge_contains_scissors)
@@ -911,20 +926,12 @@
 
 		fprintf(s->fp, "\n");
 		if (cleanup_mode == COMMIT_MSG_CLEANUP_ALL)
-			status_printf(s, GIT_COLOR_NORMAL,
-				_("Please enter the commit message for your changes."
-				  " Lines starting\nwith '%c' will be ignored, and an empty"
-				  " message aborts the commit.\n"), comment_line_char);
+			status_printf(s, GIT_COLOR_NORMAL, hint_cleanup_all, comment_line_char);
 		else if (cleanup_mode == COMMIT_MSG_CLEANUP_SCISSORS) {
 			if (whence == FROM_COMMIT && !merge_contains_scissors)
 				wt_status_add_cut_line(s->fp);
 		} else /* COMMIT_MSG_CLEANUP_SPACE, that is. */
-			status_printf(s, GIT_COLOR_NORMAL,
-				_("Please enter the commit message for your changes."
-				  " Lines starting\n"
-				  "with '%c' will be kept; you may remove them"
-				  " yourself if you want to.\n"
-				  "An empty message aborts the commit.\n"), comment_line_char);
+			status_printf(s, GIT_COLOR_NORMAL, hint_cleanup_space, comment_line_char);
 
 		/*
 		 * These should never fail because they come from our own
@@ -1510,6 +1517,9 @@
 	if (argc == 2 && !strcmp(argv[1], "-h"))
 		usage_with_options(builtin_status_usage, builtin_status_options);
 
+	prepare_repo_settings(the_repository);
+	the_repository->settings.command_requires_full_index = 0;
+
 	status_init_config(&s, git_status_config);
 	argc = parse_options(argc, argv, prefix,
 			     builtin_status_options,
diff --git a/builtin/diff.c b/builtin/diff.c
index 2d87c37..dd8ce68 100644
--- a/builtin/diff.c
+++ b/builtin/diff.c
@@ -26,8 +26,8 @@
 
 static const char builtin_diff_usage[] =
 "git diff [<options>] [<commit>] [--] [<path>...]\n"
-"   or: git diff [<options>] --cached [<commit>] [--] [<path>...]\n"
-"   or: git diff [<options>] <commit> [--merge-base] [<commit>...] <commit> [--] [<path>...]\n"
+"   or: git diff [<options>] --cached [--merge-base] [<commit>] [--] [<path>...]\n"
+"   or: git diff [<options>] [--merge-base] <commit> [<commit>...] <commit> [--] [<path>...]\n"
 "   or: git diff [<options>] <commit>...<commit>] [--] [<path>...]\n"
 "   or: git diff [<options>] <blob> <blob>]\n"
 "   or: git diff [<options>] --no-index [--] <path> <path>]\n"
diff --git a/builtin/fetch.c b/builtin/fetch.c
index 9191620..25740c1 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -1990,6 +1990,9 @@
 		fetch_config_from_gitmodules(sfjc, rs);
 	}
 
+	if (negotiate_only && !negotiation_tip.nr)
+		die(_("--negotiate-only needs one or more --negotiate-tip=*"));
+
 	if (deepen_relative) {
 		if (deepen_relative < 0)
 			die(_("Negative depth in --deepen is not supported"));
diff --git a/builtin/grep.c b/builtin/grep.c
index ab8822e..7d2f8e5 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -704,10 +704,9 @@
 static int grep_directory(struct grep_opt *opt, const struct pathspec *pathspec,
 			  int exc_std, int use_index)
 {
-	struct dir_struct dir;
+	struct dir_struct dir = DIR_INIT;
 	int i, hit = 0;
 
-	dir_init(&dir);
 	if (!use_index)
 		dir.flags |= DIR_NO_GITLINKS;
 	if (exc_std)
diff --git a/builtin/help.c b/builtin/help.c
index bb339f0..b7eec06 100644
--- a/builtin/help.c
+++ b/builtin/help.c
@@ -436,10 +436,9 @@
 		warning(_("'%s': unknown man viewer."), name);
 }
 
-static void show_man_page(const char *git_cmd)
+static void show_man_page(const char *page)
 {
 	struct man_viewer_list *viewer;
-	const char *page = cmd_to_page(git_cmd);
 	const char *fallback = getenv("GIT_MAN_VIEWER");
 
 	setup_man_path();
@@ -453,9 +452,8 @@
 	die(_("no man viewer handled the request"));
 }
 
-static void show_info_page(const char *git_cmd)
+static void show_info_page(const char *page)
 {
-	const char *page = cmd_to_page(git_cmd);
 	setenv("INFOPATH", system_path(GIT_INFO_PATH), 1);
 	execlp("info", "info", "gitman", page, (char *)NULL);
 	die(_("no info viewer handled the request"));
@@ -486,9 +484,8 @@
 	execl_git_cmd("web--browse", "-c", "help.browser", path, (char *)NULL);
 }
 
-static void show_html_page(const char *git_cmd)
+static void show_html_page(const char *page)
 {
-	const char *page = cmd_to_page(git_cmd);
 	struct strbuf page_path; /* it leaks but we exec bellow */
 
 	get_html_page_path(&page_path, page);
@@ -548,6 +545,7 @@
 {
 	int nongit;
 	enum help_format parsed_help_format;
+	const char *page;
 
 	argc = parse_options(argc, argv, prefix, builtin_help_options,
 			builtin_help_usage, 0);
@@ -606,16 +604,17 @@
 
 	argv[0] = check_git_cmd(argv[0]);
 
+	page = cmd_to_page(argv[0]);
 	switch (help_format) {
 	case HELP_FORMAT_NONE:
 	case HELP_FORMAT_MAN:
-		show_man_page(argv[0]);
+		show_man_page(page);
 		break;
 	case HELP_FORMAT_INFO:
-		show_info_page(argv[0]);
+		show_info_page(page);
 		break;
 	case HELP_FORMAT_WEB:
-		show_html_page(argv[0]);
+		show_html_page(page);
 		break;
 	}
 
diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index 3fbc5d7..8336466 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -369,9 +369,7 @@
 	use(sizeof(struct pack_header));
 }
 
-static NORETURN void bad_object(off_t offset, const char *format,
-		       ...) __attribute__((format (printf, 2, 3)));
-
+__attribute__((format (printf, 2, 3)))
 static NORETURN void bad_object(off_t offset, const char *format, ...)
 {
 	va_list params;
diff --git a/builtin/log.c b/builtin/log.c
index 516a114..3d7717b 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -245,6 +245,9 @@
 			rev->abbrev_commit = 0;
 	}
 
+	if (rev->commit_format == CMIT_FMT_USERFORMAT && !w.decorate)
+		decoration_style = 0;
+
 	if (decoration_style) {
 		const struct string_list *config_exclude =
 			repo_config_get_value_multi(the_repository,
diff --git a/builtin/ls-files.c b/builtin/ls-files.c
index 45cc3b2..29a26ad 100644
--- a/builtin/ls-files.c
+++ b/builtin/ls-files.c
@@ -608,7 +608,7 @@
 {
 	int require_work_tree = 0, show_tag = 0, i;
 	char *max_prefix;
-	struct dir_struct dir;
+	struct dir_struct dir = DIR_INIT;
 	struct pattern_list *pl;
 	struct string_list exclude_list = STRING_LIST_INIT_NODUP;
 	struct option builtin_ls_files_options[] = {
@@ -678,7 +678,6 @@
 	if (argc == 2 && !strcmp(argv[1], "-h"))
 		usage_with_options(ls_files_usage, builtin_ls_files_options);
 
-	dir_init(&dir);
 	prefix = cmd_prefix;
 	if (prefix)
 		prefix_len = strlen(prefix);
diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index a347425..2d1f97e 100644
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -425,9 +425,6 @@
 	return 0;
 }
 
-static void rp_error(const char *err, ...) __attribute__((format (printf, 1, 2)));
-static void rp_warning(const char *err, ...) __attribute__((format (printf, 1, 2)));
-
 static void report_message(const char *prefix, const char *err, va_list params)
 {
 	int sz;
@@ -445,6 +442,7 @@
 		xwrite(2, msg, sz);
 }
 
+__attribute__((format (printf, 1, 2)))
 static void rp_warning(const char *err, ...)
 {
 	va_list params;
@@ -453,6 +451,7 @@
 	va_end(params);
 }
 
+__attribute__((format (printf, 1, 2)))
 static void rp_error(const char *err, ...)
 {
 	va_list params;
diff --git a/builtin/rev-list.c b/builtin/rev-list.c
index 7677b1a..36cb909 100644
--- a/builtin/rev-list.c
+++ b/builtin/rev-list.c
@@ -127,13 +127,15 @@
 	if (info->header_prefix)
 		fputs(info->header_prefix, stdout);
 
-	if (!revs->graph)
-		fputs(get_revision_mark(revs, commit), stdout);
-	if (revs->abbrev_commit && revs->abbrev)
-		fputs(find_unique_abbrev(&commit->object.oid, revs->abbrev),
-		      stdout);
-	else
-		fputs(oid_to_hex(&commit->object.oid), stdout);
+	if (revs->include_header) {
+		if (!revs->graph)
+			fputs(get_revision_mark(revs, commit), stdout);
+		if (revs->abbrev_commit && revs->abbrev)
+			fputs(find_unique_abbrev(&commit->object.oid, revs->abbrev),
+			      stdout);
+		else
+			fputs(oid_to_hex(&commit->object.oid), stdout);
+	}
 	if (revs->print_parents) {
 		struct commit_list *parents = commit->parents;
 		while (parents) {
@@ -153,7 +155,7 @@
 	show_decorations(revs, commit);
 	if (revs->commit_format == CMIT_FMT_ONELINE)
 		putchar(' ');
-	else
+	else if (revs->include_header)
 		putchar('\n');
 
 	if (revs->verbose_header) {
@@ -512,6 +514,7 @@
 	repo_init_revisions(the_repository, &revs, prefix);
 	revs.abbrev = DEFAULT_ABBREV;
 	revs.commit_format = CMIT_FMT_UNSPECIFIED;
+	revs.include_header = 1;
 
 	/*
 	 * Scan the argument list before invoking setup_revisions(), so that we
@@ -627,6 +630,16 @@
 			continue;
 		}
 
+		if (!strcmp(arg, ("--commit-header"))) {
+			revs.include_header = 1;
+			continue;
+		}
+
+		if (!strcmp(arg, ("--no-commit-header"))) {
+			revs.include_header = 0;
+			continue;
+		}
+
 		if (!strcmp(arg, "--disk-usage")) {
 			show_disk_usage = 1;
 			info.flags |= REV_LIST_QUIET;
@@ -636,10 +649,12 @@
 		usage(rev_list_usage);
 
 	}
+	if (revs.commit_format != CMIT_FMT_USERFORMAT)
+		revs.include_header = 1;
 	if (revs.commit_format != CMIT_FMT_UNSPECIFIED) {
 		/* The command line has a --pretty  */
 		info.hdr_termination = '\n';
-		if (revs.commit_format == CMIT_FMT_ONELINE)
+		if (revs.commit_format == CMIT_FMT_ONELINE || !revs.include_header)
 			info.header_prefix = "";
 		else
 			info.header_prefix = "commit ";
diff --git a/builtin/show-branch.c b/builtin/show-branch.c
index d6d2dab..d77ce7a 100644
--- a/builtin/show-branch.c
+++ b/builtin/show-branch.c
@@ -939,9 +939,12 @@
 					mark = '*';
 				else
 					mark = '+';
-				printf("%s%c%s",
-				       get_color_code(i),
-				       mark, get_color_reset_code());
+				if (mark == ' ')
+					putchar(mark);
+				else
+					printf("%s%c%s",
+					       get_color_code(i),
+					       mark, get_color_reset_code());
 			}
 			putchar(' ');
 		}
diff --git a/builtin/stash.c b/builtin/stash.c
index 9c72e4b..8f42360 100644
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -991,9 +991,8 @@
 {
 	int i;
 	int found = 0;
-	struct dir_struct dir;
+	struct dir_struct dir = DIR_INIT;
 
-	dir_init(&dir);
 	if (include_untracked != INCLUDE_ALL_FILES)
 		setup_standard_excludes(&dir);
 
diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index ae6174a..f73963a 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -19,7 +19,6 @@
 #include "diffcore.h"
 #include "diff.h"
 #include "object-store.h"
-#include "dir.h"
 #include "advice.h"
 
 #define OPT_QUIET (1 << 0)
diff --git a/builtin/worktree.c b/builtin/worktree.c
index 976bf8e..0d0a80d 100644
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -30,7 +30,7 @@
 	int detach;
 	int quiet;
 	int checkout;
-	int keep_locked;
+	const char *keep_locked;
 };
 
 static int show_only;
@@ -302,10 +302,10 @@
 	 * after the preparation is over.
 	 */
 	strbuf_addf(&sb, "%s/locked", sb_repo.buf);
-	if (!opts->keep_locked)
-		write_file(sb.buf, "initializing");
+	if (opts->keep_locked)
+		write_file(sb.buf, "%s", opts->keep_locked);
 	else
-		write_file(sb.buf, "added with --lock");
+		write_file(sb.buf, _("initializing"));
 
 	strbuf_addf(&sb_git, "%s/.git", path);
 	if (safe_create_leading_directories_const(sb_git.buf))
@@ -475,6 +475,8 @@
 	const char *branch;
 	const char *new_branch = NULL;
 	const char *opt_track = NULL;
+	const char *lock_reason = NULL;
+	int keep_locked = 0;
 	struct option options[] = {
 		OPT__FORCE(&opts.force,
 			   N_("checkout <branch> even if already checked out in other worktree"),
@@ -485,7 +487,9 @@
 			   N_("create or reset a branch")),
 		OPT_BOOL('d', "detach", &opts.detach, N_("detach HEAD at named commit")),
 		OPT_BOOL(0, "checkout", &opts.checkout, N_("populate the new working tree")),
-		OPT_BOOL(0, "lock", &opts.keep_locked, N_("keep the new working tree locked")),
+		OPT_BOOL(0, "lock", &keep_locked, N_("keep the new working tree locked")),
+		OPT_STRING(0, "reason", &lock_reason, N_("string"),
+			   N_("reason for locking")),
 		OPT__QUIET(&opts.quiet, N_("suppress progress reporting")),
 		OPT_PASSTHRU(0, "track", &opt_track, NULL,
 			     N_("set up tracking mode (see git-branch(1))"),
@@ -500,6 +504,13 @@
 	ac = parse_options(ac, av, prefix, options, worktree_usage, 0);
 	if (!!opts.detach + !!new_branch + !!new_branch_force > 1)
 		die(_("-b, -B, and --detach are mutually exclusive"));
+	if (lock_reason && !keep_locked)
+		die(_("--reason requires --lock"));
+	if (lock_reason)
+		opts.keep_locked = lock_reason;
+	else if (keep_locked)
+		opts.keep_locked = _("added with --lock");
+
 	if (ac < 1 || ac > 2)
 		usage_with_options(worktree_usage, options);
 
diff --git a/bundle.c b/bundle.c
index 693d619..ab63f40 100644
--- a/bundle.c
+++ b/bundle.c
@@ -23,13 +23,16 @@
 	{ 3, v3_bundle_signature },
 };
 
-static void add_to_ref_list(const struct object_id *oid, const char *name,
-		struct ref_list *list)
+void bundle_header_init(struct bundle_header *header)
 {
-	ALLOC_GROW(list->list, list->nr + 1, list->alloc);
-	oidcpy(&list->list[list->nr].oid, oid);
-	list->list[list->nr].name = xstrdup(name);
-	list->nr++;
+	struct bundle_header blank = BUNDLE_HEADER_INIT;
+	memcpy(header, &blank, sizeof(*header));
+}
+
+void bundle_header_release(struct bundle_header *header)
+{
+	string_list_clear(&header->prerequisites, 1);
+	string_list_clear(&header->references, 1);
 }
 
 static int parse_capability(struct bundle_header *header, const char *capability)
@@ -112,10 +115,11 @@
 			status = -1;
 			break;
 		} else {
+			struct object_id *dup = oiddup(&oid);
 			if (is_prereq)
-				add_to_ref_list(&oid, "", &header->prerequisites);
+				string_list_append(&header->prerequisites, "")->util = dup;
 			else
-				add_to_ref_list(&oid, p + 1, &header->references);
+				string_list_append(&header->references, p + 1)->util = dup;
 		}
 	}
 
@@ -139,33 +143,38 @@
 
 int is_bundle(const char *path, int quiet)
 {
-	struct bundle_header header;
+	struct bundle_header header = BUNDLE_HEADER_INIT;
 	int fd = open(path, O_RDONLY);
 
 	if (fd < 0)
 		return 0;
-	memset(&header, 0, sizeof(header));
 	fd = parse_bundle_header(fd, &header, quiet ? NULL : path);
 	if (fd >= 0)
 		close(fd);
+	bundle_header_release(&header);
 	return (fd >= 0);
 }
 
-static int list_refs(struct ref_list *r, int argc, const char **argv)
+static int list_refs(struct string_list *r, int argc, const char **argv)
 {
 	int i;
 
 	for (i = 0; i < r->nr; i++) {
+		struct object_id *oid;
+		const char *name;
+
 		if (argc > 1) {
 			int j;
 			for (j = 1; j < argc; j++)
-				if (!strcmp(r->list[i].name, argv[j]))
+				if (!strcmp(r->items[i].string, argv[j]))
 					break;
 			if (j == argc)
 				continue;
 		}
-		printf("%s %s\n", oid_to_hex(&r->list[i].oid),
-				r->list[i].name);
+
+		oid = r->items[i].util;
+		name = r->items[i].string;
+		printf("%s %s\n", oid_to_hex(oid), name);
 	}
 	return 0;
 }
@@ -181,7 +190,7 @@
 	 * Do fast check, then if any prereqs are missing then go line by line
 	 * to be verbose about the errors
 	 */
-	struct ref_list *p = &header->prerequisites;
+	struct string_list *p = &header->prerequisites;
 	struct rev_info revs;
 	const char *argv[] = {NULL, "--all", NULL};
 	struct commit *commit;
@@ -193,16 +202,18 @@
 
 	repo_init_revisions(r, &revs, NULL);
 	for (i = 0; i < p->nr; i++) {
-		struct ref_list_entry *e = p->list + i;
-		struct object *o = parse_object(r, &e->oid);
+		struct string_list_item *e = p->items + i;
+		const char *name = e->string;
+		struct object_id *oid = e->util;
+		struct object *o = parse_object(r, oid);
 		if (o) {
 			o->flags |= PREREQ_MARK;
-			add_pending_object(&revs, o, e->name);
+			add_pending_object(&revs, o, name);
 			continue;
 		}
 		if (++ret == 1)
 			error("%s", message);
-		error("%s %s", oid_to_hex(&e->oid), e->name);
+		error("%s %s", oid_to_hex(oid), name);
 	}
 	if (revs.pending.nr != p->nr)
 		return ret;
@@ -218,26 +229,29 @@
 			i--;
 
 	for (i = 0; i < p->nr; i++) {
-		struct ref_list_entry *e = p->list + i;
-		struct object *o = parse_object(r, &e->oid);
+		struct string_list_item *e = p->items + i;
+		const char *name = e->string;
+		const struct object_id *oid = e->util;
+		struct object *o = parse_object(r, oid);
 		assert(o); /* otherwise we'd have returned early */
 		if (o->flags & SHOWN)
 			continue;
 		if (++ret == 1)
 			error("%s", message);
-		error("%s %s", oid_to_hex(&e->oid), e->name);
+		error("%s %s", oid_to_hex(oid), name);
 	}
 
 	/* Clean up objects used, as they will be reused. */
 	for (i = 0; i < p->nr; i++) {
-		struct ref_list_entry *e = p->list + i;
-		commit = lookup_commit_reference_gently(r, &e->oid, 1);
+		struct string_list_item *e = p->items + i;
+		struct object_id *oid = e->util;
+		commit = lookup_commit_reference_gently(r, oid, 1);
 		if (commit)
 			clear_commit_marks(commit, ALL_REV_FLAGS);
 	}
 
 	if (verbose) {
-		struct ref_list *r;
+		struct string_list *r;
 
 		r = &header->references;
 		printf_ln(Q_("The bundle contains this ref:",
diff --git a/bundle.h b/bundle.h
index f9e2d1c..1927d8c 100644
--- a/bundle.h
+++ b/bundle.h
@@ -3,22 +3,23 @@
 
 #include "strvec.h"
 #include "cache.h"
-
-struct ref_list {
-	unsigned int nr, alloc;
-	struct ref_list_entry {
-		struct object_id oid;
-		char *name;
-	} *list;
-};
+#include "string-list.h"
 
 struct bundle_header {
 	unsigned version;
-	struct ref_list prerequisites;
-	struct ref_list references;
+	struct string_list prerequisites;
+	struct string_list references;
 	const struct git_hash_algo *hash_algo;
 };
 
+#define BUNDLE_HEADER_INIT \
+{ \
+	.prerequisites = STRING_LIST_INIT_DUP, \
+	.references = STRING_LIST_INIT_DUP, \
+}
+void bundle_header_init(struct bundle_header *header);
+void bundle_header_release(struct bundle_header *header);
+
 int is_bundle(const char *path, int quiet);
 int read_bundle_header(const char *path, struct bundle_header *header);
 int create_bundle(struct repository *r, const char *path,
diff --git a/cache.h b/cache.h
index ba04ff8..f9aed2d 100644
--- a/cache.h
+++ b/cache.h
@@ -1385,6 +1385,7 @@
 };
 
 int repo_get_oid(struct repository *r, const char *str, struct object_id *oid);
+__attribute__((format (printf, 2, 3)))
 int get_oidf(struct object_id *oid, const char *fmt, ...);
 int repo_get_oid_commit(struct repository *r, const char *str, struct object_id *oid);
 int repo_get_oid_committish(struct repository *r, const char *str, struct object_id *oid);
diff --git a/cbtree.c b/cbtree.c
new file mode 100644
index 0000000..b0c65d8
--- /dev/null
+++ b/cbtree.c
@@ -0,0 +1,167 @@
+/*
+ * crit-bit tree implementation, does no allocations internally
+ * For more information on crit-bit trees: https://cr.yp.to/critbit.html
+ * Based on Adam Langley's adaptation of Dan Bernstein's public domain code
+ * git clone https://github.com/agl/critbit.git
+ */
+#include "cbtree.h"
+
+static struct cb_node *cb_node_of(const void *p)
+{
+	return (struct cb_node *)((uintptr_t)p - 1);
+}
+
+/* locate the best match, does not do a final comparision */
+static struct cb_node *cb_internal_best_match(struct cb_node *p,
+					const uint8_t *k, size_t klen)
+{
+	while (1 & (uintptr_t)p) {
+		struct cb_node *q = cb_node_of(p);
+		uint8_t c = q->byte < klen ? k[q->byte] : 0;
+		size_t direction = (1 + (q->otherbits | c)) >> 8;
+
+		p = q->child[direction];
+	}
+	return p;
+}
+
+/* returns NULL if successful, existing cb_node if duplicate */
+struct cb_node *cb_insert(struct cb_tree *t, struct cb_node *node, size_t klen)
+{
+	size_t newbyte, newotherbits;
+	uint8_t c;
+	int newdirection;
+	struct cb_node **wherep, *p;
+
+	assert(!((uintptr_t)node & 1)); /* allocations must be aligned */
+
+	if (!t->root) {		/* insert into empty tree */
+		t->root = node;
+		return NULL;	/* success */
+	}
+
+	/* see if a node already exists */
+	p = cb_internal_best_match(t->root, node->k, klen);
+
+	/* find first differing byte */
+	for (newbyte = 0; newbyte < klen; newbyte++) {
+		if (p->k[newbyte] != node->k[newbyte])
+			goto different_byte_found;
+	}
+	return p;	/* element exists, let user deal with it */
+
+different_byte_found:
+	newotherbits = p->k[newbyte] ^ node->k[newbyte];
+	newotherbits |= newotherbits >> 1;
+	newotherbits |= newotherbits >> 2;
+	newotherbits |= newotherbits >> 4;
+	newotherbits = (newotherbits & ~(newotherbits >> 1)) ^ 255;
+	c = p->k[newbyte];
+	newdirection = (1 + (newotherbits | c)) >> 8;
+
+	node->byte = newbyte;
+	node->otherbits = newotherbits;
+	node->child[1 - newdirection] = node;
+
+	/* find a place to insert it */
+	wherep = &t->root;
+	for (;;) {
+		struct cb_node *q;
+		size_t direction;
+
+		p = *wherep;
+		if (!(1 & (uintptr_t)p))
+			break;
+		q = cb_node_of(p);
+		if (q->byte > newbyte)
+			break;
+		if (q->byte == newbyte && q->otherbits > newotherbits)
+			break;
+		c = q->byte < klen ? node->k[q->byte] : 0;
+		direction = (1 + (q->otherbits | c)) >> 8;
+		wherep = q->child + direction;
+	}
+
+	node->child[newdirection] = *wherep;
+	*wherep = (struct cb_node *)(1 + (uintptr_t)node);
+
+	return NULL; /* success */
+}
+
+struct cb_node *cb_lookup(struct cb_tree *t, const uint8_t *k, size_t klen)
+{
+	struct cb_node *p = cb_internal_best_match(t->root, k, klen);
+
+	return p && !memcmp(p->k, k, klen) ? p : NULL;
+}
+
+struct cb_node *cb_unlink(struct cb_tree *t, const uint8_t *k, size_t klen)
+{
+	struct cb_node **wherep = &t->root;
+	struct cb_node **whereq = NULL;
+	struct cb_node *q = NULL;
+	size_t direction = 0;
+	uint8_t c;
+	struct cb_node *p = t->root;
+
+	if (!p) return NULL;	/* empty tree, nothing to delete */
+
+	/* traverse to find best match, keeping link to parent */
+	while (1 & (uintptr_t)p) {
+		whereq = wherep;
+		q = cb_node_of(p);
+		c = q->byte < klen ? k[q->byte] : 0;
+		direction = (1 + (q->otherbits | c)) >> 8;
+		wherep = q->child + direction;
+		p = *wherep;
+	}
+
+	if (memcmp(p->k, k, klen))
+		return NULL;		/* no match, nothing unlinked */
+
+	/* found an exact match */
+	if (whereq)	/* update parent */
+		*whereq = q->child[1 - direction];
+	else
+		t->root = NULL;
+	return p;
+}
+
+static enum cb_next cb_descend(struct cb_node *p, cb_iter fn, void *arg)
+{
+	if (1 & (uintptr_t)p) {
+		struct cb_node *q = cb_node_of(p);
+		enum cb_next n = cb_descend(q->child[0], fn, arg);
+
+		return n == CB_BREAK ? n : cb_descend(q->child[1], fn, arg);
+	} else {
+		return fn(p, arg);
+	}
+}
+
+void cb_each(struct cb_tree *t, const uint8_t *kpfx, size_t klen,
+			cb_iter fn, void *arg)
+{
+	struct cb_node *p = t->root;
+	struct cb_node *top = p;
+	size_t i = 0;
+
+	if (!p) return; /* empty tree */
+
+	/* Walk tree, maintaining top pointer */
+	while (1 & (uintptr_t)p) {
+		struct cb_node *q = cb_node_of(p);
+		uint8_t c = q->byte < klen ? kpfx[q->byte] : 0;
+		size_t direction = (1 + (q->otherbits | c)) >> 8;
+
+		p = q->child[direction];
+		if (q->byte < klen)
+			top = p;
+	}
+
+	for (i = 0; i < klen; i++) {
+		if (p->k[i] != kpfx[i])
+			return; /* "best" match failed */
+	}
+	cb_descend(top, fn, arg);
+}
diff --git a/cbtree.h b/cbtree.h
new file mode 100644
index 0000000..fe45870
--- /dev/null
+++ b/cbtree.h
@@ -0,0 +1,56 @@
+/*
+ * crit-bit tree implementation, does no allocations internally
+ * For more information on crit-bit trees: https://cr.yp.to/critbit.html
+ * Based on Adam Langley's adaptation of Dan Bernstein's public domain code
+ * git clone https://github.com/agl/critbit.git
+ *
+ * This is adapted to store arbitrary data (not just NUL-terminated C strings
+ * and allocates no memory internally.  The user needs to allocate
+ * "struct cb_node" and fill cb_node.k[] with arbitrary match data
+ * for memcmp.
+ * If "klen" is variable, then it should be embedded into "c_node.k[]"
+ * Recursion is bound by the maximum value of "klen" used.
+ */
+#ifndef CBTREE_H
+#define CBTREE_H
+
+#include "git-compat-util.h"
+
+struct cb_node;
+struct cb_node {
+	struct cb_node *child[2];
+	/*
+	 * n.b. uint32_t for `byte' is excessive for OIDs,
+	 * we may consider shorter variants if nothing else gets stored.
+	 */
+	uint32_t byte;
+	uint8_t otherbits;
+	uint8_t k[FLEX_ARRAY]; /* arbitrary data */
+};
+
+struct cb_tree {
+	struct cb_node *root;
+};
+
+enum cb_next {
+	CB_CONTINUE = 0,
+	CB_BREAK = 1
+};
+
+#define CBTREE_INIT { .root = NULL }
+
+static inline void cb_init(struct cb_tree *t)
+{
+	t->root = NULL;
+}
+
+struct cb_node *cb_lookup(struct cb_tree *, const uint8_t *k, size_t klen);
+struct cb_node *cb_insert(struct cb_tree *, struct cb_node *, size_t klen);
+struct cb_node *cb_unlink(struct cb_tree *t, const uint8_t *k, size_t klen);
+
+typedef enum cb_next (*cb_iter)(struct cb_node *, void *arg);
+
+void cb_each(struct cb_tree *, const uint8_t *kpfx, size_t klen,
+		cb_iter, void *arg);
+
+#endif /* CBTREE_H */
diff --git a/ci/install-dependencies.sh b/ci/install-dependencies.sh
index 67852d0..5772081 100755
--- a/ci/install-dependencies.sh
+++ b/ci/install-dependencies.sh
@@ -65,6 +65,11 @@
 	sudo apt-get -q -y install coccinelle libcurl4-openssl-dev libssl-dev \
 		libexpat-dev gettext make
 	;;
+sparse)
+	sudo apt-get -q update -q
+	sudo apt-get -q -y install libssl-dev libcurl4-openssl-dev \
+		libexpat-dev gettext zlib1g-dev
+	;;
 Documentation)
 	sudo apt-get -q update
 	sudo apt-get -q -y install asciidoc xmlto docbook-xsl-ns make
diff --git a/commit-graph.c b/commit-graph.c
index 2bcb4e0..3860a0d 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -2408,6 +2408,7 @@
 #define VERIFY_COMMIT_GRAPH_ERROR_HASH 2
 static int verify_commit_graph_error;
 
+__attribute__((format (printf, 1, 2)))
 static void graph_report(const char *fmt, ...)
 {
 	va_list ap;
@@ -2422,14 +2423,16 @@
 #define GENERATION_ZERO_EXISTS 1
 #define GENERATION_NUMBER_EXISTS 2
 
+static int commit_graph_checksum_valid(struct commit_graph *g)
+{
+	return hashfile_checksum_valid(g->data, g->data_len);
+}
+
 int verify_commit_graph(struct repository *r, struct commit_graph *g, int flags)
 {
 	uint32_t i, cur_fanout_pos = 0;
 	struct object_id prev_oid, cur_oid;
-	unsigned char checksum[GIT_MAX_HEXSZ];
 	int generation_zero = 0;
-	struct hashfile *f;
-	int devnull;
 	struct progress *progress = NULL;
 	int local_error = 0;
 
@@ -2442,11 +2445,7 @@
 	if (verify_commit_graph_error)
 		return verify_commit_graph_error;
 
-	devnull = open("/dev/null", O_WRONLY);
-	f = hashfd(devnull, NULL);
-	hashwrite(f, g->data, g->data_len - g->hash_len);
-	finalize_hashfile(f, checksum, CSUM_CLOSE);
-	if (!hasheq(checksum, g->data + g->data_len - g->hash_len)) {
+	if (!commit_graph_checksum_valid(g)) {
 		graph_report(_("the commit-graph file has incorrect checksum and is likely corrupt"));
 		verify_commit_graph_error = VERIFY_COMMIT_GRAPH_ERROR_HASH;
 	}
diff --git a/commit.c b/commit.c
index 8ea55a4..143f472 100644
--- a/commit.c
+++ b/commit.c
@@ -1178,7 +1178,7 @@
 	/*
 	 * We could verify this signature and either omit the tag when
 	 * it does not validate, but the integrator may not have the
-	 * public key of the signer of the tag he is merging, while a
+	 * public key of the signer of the tag being merged, while a
 	 * later auditor may have it while auditing, so let's not run
 	 * verify-signed-buffer here for now...
 	 *
diff --git a/config.c b/config.c
index f9c400a..f33abea 100644
--- a/config.c
+++ b/config.c
@@ -1833,9 +1833,10 @@
 char *git_system_config(void)
 {
 	char *system_config = xstrdup_or_null(getenv("GIT_CONFIG_SYSTEM"));
-	if (system_config)
-		return system_config;
-	return system_path(ETC_GITCONFIG);
+	if (!system_config)
+		system_config = system_path(ETC_GITCONFIG);
+	normalize_path_copy(system_config, system_config);
+	return system_config;
 }
 
 void git_global_config(char **user_out, char **xdg_out)
@@ -2072,7 +2073,7 @@
 		e = xmalloc(sizeof(*e));
 		hashmap_entry_init(&e->ent, strhash(key));
 		e->key = xstrdup(key);
-		string_list_init(&e->value_list, 1);
+		string_list_init_dup(&e->value_list);
 		hashmap_add(&cs->config_hash, &e->ent);
 	}
 	si = string_list_append_nodup(&e->value_list, xstrdup_or_null(value));
@@ -2837,7 +2838,7 @@
 	begin = store->parsed[i].begin;
 
 	/*
-	 * Next, make sure that we are removing he last key(s) in the section,
+	 * Next, make sure that we are removing the last key(s) in the section,
 	 * and that there are no comments that are possibly about the current
 	 * section.
 	 */
@@ -3051,7 +3052,8 @@
 		if (contents == MAP_FAILED) {
 			if (errno == ENODEV && S_ISDIR(st.st_mode))
 				errno = EISDIR;
-			error_errno(_("unable to mmap '%s'"), config_filename);
+			error_errno(_("unable to mmap '%s'%s"),
+					config_filename, mmap_os_err());
 			ret = CONFIG_INVALID_FILE;
 			contents = NULL;
 			goto out_free;
diff --git a/config.h b/config.h
index 9038538..a2200f3 100644
--- a/config.h
+++ b/config.h
@@ -450,8 +450,8 @@
 /**
  * Parses the file and adds the variable-value pairs to the `config_set`,
  * dies if there is an error in parsing the file. Returns 0 on success, or
- * -1 if the file does not exist or is inaccessible. The user has to decide
- * if he wants to free the incomplete configset or continue using it when
+ * -1 if the file does not exist or is inaccessible. The caller decides
+ * whether to free the incomplete configset or continue using it when
  * the function returns -1.
  */
 int git_configset_add_file(struct config_set *cs, const char *filename);
diff --git a/config.mak.uname b/config.mak.uname
index cb443b4..69413fb 100644
--- a/config.mak.uname
+++ b/config.mak.uname
@@ -437,6 +437,11 @@
 	NO_POSIX_GOODIES = UnfortunatelyYes
 	NATIVE_CRLF = YesPlease
 	DEFAULT_HELP_FORMAT = html
+ifeq (/mingw64,$(subst 32,64,$(prefix)))
+	# Move system config into top-level /etc/
+	ETC_GITCONFIG = ../etc/gitconfig
+	ETC_GITATTRIBUTES = ../etc/gitattributes
+endif
 
 	CC = compat/vcbuild/scripts/clink.pl
 	AR = compat/vcbuild/scripts/lib.pl
@@ -668,9 +673,14 @@
 		HAVE_LIBCHARSET_H = YesPlease
 		NO_GETTEXT =
 		USE_GETTEXT_SCHEME = fallthrough
-		USE_LIBPCRE= YesPlease
+		USE_LIBPCRE = YesPlease
 		NO_CURL =
 		USE_NED_ALLOCATOR = YesPlease
+		ifeq (/mingw64,$(subst 32,64,$(prefix)))
+			# Move system config into top-level /etc/
+			ETC_GITCONFIG = ../etc/gitconfig
+			ETC_GITATTRIBUTES = ../etc/gitattributes
+		endif
 	else
 		COMPAT_CFLAGS += -D__USE_MINGW_ANSI_STDIO
 		NO_CURL = YesPlease
diff --git a/contrib/buildsystems/CMakeLists.txt b/contrib/buildsystems/CMakeLists.txt
index 3dc7ffc..171b412 100644
--- a/contrib/buildsystems/CMakeLists.txt
+++ b/contrib/buildsystems/CMakeLists.txt
@@ -223,8 +223,6 @@
 
 
 add_compile_definitions(PAGER_ENV="LESS=FRX LV=-c"
-			ETC_GITATTRIBUTES="etc/gitattributes"
-			ETC_GITCONFIG="etc/gitconfig"
 			GIT_EXEC_PATH="libexec/git-core"
 			GIT_LOCALE_PATH="share/locale"
 			GIT_MAN_PATH="share/man"
@@ -239,10 +237,15 @@
 
 if(WIN32)
 	set(FALLBACK_RUNTIME_PREFIX /mingw64)
-	add_compile_definitions(FALLBACK_RUNTIME_PREFIX="${FALLBACK_RUNTIME_PREFIX}")
+	# Move system config into top-level /etc/
+	add_compile_definitions(FALLBACK_RUNTIME_PREFIX="${FALLBACK_RUNTIME_PREFIX}"
+		ETC_GITATTRIBUTES="../etc/gitattributes"
+		ETC_GITCONFIG="../etc/gitconfig")
 else()
 	set(FALLBACK_RUNTIME_PREFIX /home/$ENV{USER})
-	add_compile_definitions(FALLBACK_RUNTIME_PREFIX="${FALLBACK_RUNTIME_PREFIX}")
+	add_compile_definitions(FALLBACK_RUNTIME_PREFIX="${FALLBACK_RUNTIME_PREFIX}"
+		ETC_GITATTRIBUTES="etc/gitattributes"
+		ETC_GITCONFIG="etc/gitconfig")
 endif()
 
 
diff --git a/contrib/credential/osxkeychain/git-credential-osxkeychain.c b/contrib/credential/osxkeychain/git-credential-osxkeychain.c
index bcd3f57..0b44a9b 100644
--- a/contrib/credential/osxkeychain/git-credential-osxkeychain.c
+++ b/contrib/credential/osxkeychain/git-credential-osxkeychain.c
@@ -10,6 +10,7 @@
 static char *password;
 static UInt16 port;
 
+__attribute__((format (printf, 1, 2)))
 static void die(const char *err, ...)
 {
 	char msg[4096];
diff --git a/contrib/credential/wincred/git-credential-wincred.c b/contrib/credential/wincred/git-credential-wincred.c
index 5bdad41..5091048 100644
--- a/contrib/credential/wincred/git-credential-wincred.c
+++ b/contrib/credential/wincred/git-credential-wincred.c
@@ -11,6 +11,7 @@
 
 #define ARRAY_SIZE(x) (sizeof(x)/sizeof(x[0]))
 
+__attribute__((format (printf, 1, 2)))
 static void die(const char *err, ...)
 {
 	char msg[4096];
diff --git a/credential.c b/credential.c
index e5202fb..3c05c7c 100644
--- a/credential.c
+++ b/credential.c
@@ -10,8 +10,8 @@
 
 void credential_init(struct credential *c)
 {
-	memset(c, 0, sizeof(*c));
-	c->helpers.strdup_strings = 1;
+	struct credential blank = CREDENTIAL_INIT;
+	memcpy(c, &blank, sizeof(*c));
 }
 
 void credential_clear(struct credential *c)
diff --git a/credential.h b/credential.h
index c0e17e3..f430e77 100644
--- a/credential.h
+++ b/credential.h
@@ -128,7 +128,9 @@
 	char *path;
 };
 
-#define CREDENTIAL_INIT { STRING_LIST_INIT_DUP }
+#define CREDENTIAL_INIT { \
+	.helpers = STRING_LIST_INIT_DUP, \
+}
 
 /* Initialize a credential structure, setting all fields to empty. */
 void credential_init(struct credential *);
diff --git a/csum-file.c b/csum-file.c
index 3487d28..c951cf8 100644
--- a/csum-file.c
+++ b/csum-file.c
@@ -217,3 +217,19 @@
 	f->do_crc = 0;
 	return f->crc32;
 }
+
+int hashfile_checksum_valid(const unsigned char *data, size_t total_len)
+{
+	unsigned char got[GIT_MAX_RAWSZ];
+	git_hash_ctx ctx;
+	size_t data_len = total_len - the_hash_algo->rawsz;
+
+	if (total_len < the_hash_algo->rawsz)
+		return 0; /* say "too short"? */
+
+	the_hash_algo->init_fn(&ctx);
+	the_hash_algo->update_fn(&ctx, data, data_len);
+	the_hash_algo->final_fn(got, &ctx);
+
+	return hasheq(got, data + data_len);
+}
diff --git a/csum-file.h b/csum-file.h
index 3044bd1..291215b 100644
--- a/csum-file.h
+++ b/csum-file.h
@@ -44,6 +44,9 @@
 void crc32_begin(struct hashfile *);
 uint32_t crc32_end(struct hashfile *);
 
+/* Verify checksum validity while reading. Returns non-zero on success. */
+int hashfile_checksum_valid(const unsigned char *data, size_t len);
+
 /*
  * Returns the total number of bytes fed to the hashfile so far (including ones
  * that have not been written out to the descriptor yet).
diff --git a/date.c b/date.c
index f9ea807..c55ea47 100644
--- a/date.c
+++ b/date.c
@@ -908,7 +908,7 @@
 		/*
 		 * We take over "now" here, which usually translates
 		 * to the current timestamp.  This is because the user
-		 * really means to expire everything she has done in
+		 * really means to expire everything that was done in
 		 * the past, and by definition reflogs are the record
 		 * of the past, and there is nothing from the future
 		 * to be kept.
diff --git a/diff-lib.c b/diff-lib.c
index c2ac925..f9eadc4 100644
--- a/diff-lib.c
+++ b/diff-lib.c
@@ -325,6 +325,11 @@
 	unsigned dirty_submodule = 0;
 	struct index_state *istate = revs->diffopt.repo->index;
 
+	if (new_file && S_ISSPARSEDIR(new_file->ce_mode)) {
+		diff_tree_oid(NULL, &new_file->oid, new_file->name, &revs->diffopt);
+		return;
+	}
+
 	/*
 	 * New file in the index: it might actually be different in
 	 * the working tree.
@@ -347,6 +352,20 @@
 	unsigned dirty_submodule = 0;
 	struct index_state *istate = revs->diffopt.repo->index;
 
+	assert(S_ISSPARSEDIR(old_entry->ce_mode) ==
+	       S_ISSPARSEDIR(new_entry->ce_mode));
+
+	/*
+	 * If both are sparse directory entries, then expand the
+	 * modifications to the file level. If only one was a sparse
+	 * directory, then they appear as an add and delete instead of
+	 * a modification.
+	 */
+	if (S_ISSPARSEDIR(new_entry->ce_mode)) {
+		diff_tree_oid(&old_entry->oid, &new_entry->oid, new_entry->name, &revs->diffopt);
+		return 0;
+	}
+
 	if (get_stat_data(istate, new_entry, &oid, &mode, cached, match_missing,
 			  &dirty_submodule, &revs->diffopt) < 0) {
 		if (report_missing)
diff --git a/diff.c b/diff.c
index 260dc37..82f88de 100644
--- a/diff.c
+++ b/diff.c
@@ -35,7 +35,7 @@
 
 static int diff_detect_rename_default;
 static int diff_indent_heuristic = 1;
-static int diff_rename_limit_default = 400;
+static int diff_rename_limit_default = 1000;
 static int diff_suppress_blank_empty;
 static int diff_use_color_default = -1;
 static int diff_color_moved_default;
@@ -6295,7 +6295,7 @@
 }
 
 static const char rename_limit_warning[] =
-N_("inexact rename detection was skipped due to too many files.");
+N_("exhaustive rename detection was skipped due to too many files.");
 
 static const char degrade_cc_to_c_warning[] =
 N_("only found copies from modified paths due to too many files.");
diff --git a/diffcore-rename.c b/diffcore-rename.c
index 3375e24..2618bb0 100644
--- a/diffcore-rename.c
+++ b/diffcore-rename.c
@@ -54,7 +54,7 @@
 	if (p->broken_pair) {
 		if (!break_idx) {
 			break_idx = xmalloc(sizeof(*break_idx));
-			strintmap_init(break_idx, -1);
+			strintmap_init_with_options(break_idx, -1, NULL, 0);
 		}
 		strintmap_set(break_idx, p->one->path, rename_dst_nr);
 	}
@@ -87,13 +87,13 @@
 	short name_score;
 };
 
-struct prefetch_options {
+struct inexact_prefetch_options {
 	struct repository *repo;
 	int skip_unmodified;
 };
-static void prefetch(void *prefetch_options)
+static void inexact_prefetch(void *prefetch_options)
 {
-	struct prefetch_options *options = prefetch_options;
+	struct inexact_prefetch_options *options = prefetch_options;
 	int i;
 	struct oid_array to_fetch = OID_ARRAY_INIT;
 
@@ -126,7 +126,7 @@
 			       struct diff_filespec *src,
 			       struct diff_filespec *dst,
 			       int minimum_score,
-			       int skip_unmodified)
+			       struct diff_populate_filespec_options *dpf_opt)
 {
 	/* src points at a file that existed in the original tree (or
 	 * optionally a file in the destination tree) and dst points
@@ -143,15 +143,6 @@
 	 */
 	unsigned long max_size, delta_size, base_size, src_copied, literal_added;
 	int score;
-	struct diff_populate_filespec_options dpf_options = {
-		.check_size_only = 1
-	};
-	struct prefetch_options prefetch_options = {r, skip_unmodified};
-
-	if (r == the_repository && has_promisor_remote()) {
-		dpf_options.missing_object_cb = prefetch;
-		dpf_options.missing_object_data = &prefetch_options;
-	}
 
 	/* We deal only with regular files.  Symlink renames are handled
 	 * only when they are exact matches --- in other words, no edits
@@ -169,11 +160,13 @@
 	 * is a possible size - we really should have a flag to
 	 * say whether the size is valid or not!)
 	 */
+	dpf_opt->check_size_only = 1;
+
 	if (!src->cnt_data &&
-	    diff_populate_filespec(r, src, &dpf_options))
+	    diff_populate_filespec(r, src, dpf_opt))
 		return 0;
 	if (!dst->cnt_data &&
-	    diff_populate_filespec(r, dst, &dpf_options))
+	    diff_populate_filespec(r, dst, dpf_opt))
 		return 0;
 
 	max_size = ((src->size > dst->size) ? src->size : dst->size);
@@ -191,11 +184,11 @@
 	if (max_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
 		return 0;
 
-	dpf_options.check_size_only = 0;
+	dpf_opt->check_size_only = 0;
 
-	if (!src->cnt_data && diff_populate_filespec(r, src, &dpf_options))
+	if (!src->cnt_data && diff_populate_filespec(r, src, dpf_opt))
 		return 0;
-	if (!dst->cnt_data && diff_populate_filespec(r, dst, &dpf_options))
+	if (!dst->cnt_data && diff_populate_filespec(r, dst, dpf_opt))
 		return 0;
 
 	if (diffcore_count_changes(r, src, dst,
@@ -823,6 +816,78 @@
 	return idx;
 }
 
+struct basename_prefetch_options {
+	struct repository *repo;
+	struct strintmap *relevant_sources;
+	struct strintmap *sources;
+	struct strintmap *dests;
+	struct dir_rename_info *info;
+};
+static void basename_prefetch(void *prefetch_options)
+{
+	struct basename_prefetch_options *options = prefetch_options;
+	struct strintmap *relevant_sources = options->relevant_sources;
+	struct strintmap *sources = options->sources;
+	struct strintmap *dests = options->dests;
+	struct dir_rename_info *info = options->info;
+	int i;
+	struct oid_array to_fetch = OID_ARRAY_INIT;
+
+	/*
+	 * TODO: The following loops mirror the code/logic from
+	 * find_basename_matches(), though not quite exactly.  Maybe
+	 * abstract the iteration logic out somehow?
+	 */
+	for (i = 0; i < rename_src_nr; ++i) {
+		char *filename = rename_src[i].p->one->path;
+		const char *base = NULL;
+		intptr_t src_index;
+		intptr_t dst_index;
+
+		/* Skip irrelevant sources */
+		if (relevant_sources &&
+		    !strintmap_contains(relevant_sources, filename))
+			continue;
+
+		/*
+		 * If the basename is unique among remaining sources, then
+		 * src_index will equal 'i' and we can attempt to match it
+		 * to a unique basename in the destinations.  Otherwise,
+		 * use directory rename heuristics, if possible.
+		 */
+		base = get_basename(filename);
+		src_index = strintmap_get(sources, base);
+		assert(src_index == -1 || src_index == i);
+
+		if (strintmap_contains(dests, base)) {
+			struct diff_filespec *one, *two;
+
+			/* Find a matching destination, if possible */
+			dst_index = strintmap_get(dests, base);
+			if (src_index == -1 || dst_index == -1) {
+				src_index = i;
+				dst_index = idx_possible_rename(filename, info);
+			}
+			if (dst_index == -1)
+				continue;
+
+			/* Ignore this dest if already used in a rename */
+			if (rename_dst[dst_index].is_rename)
+				continue; /* already used previously */
+
+			one = rename_src[src_index].p->one;
+			two = rename_dst[dst_index].p->two;
+
+			/* Add the pairs */
+			diff_add_if_missing(options->repo, &to_fetch, two);
+			diff_add_if_missing(options->repo, &to_fetch, one);
+		}
+	}
+
+	promisor_remote_get_direct(options->repo, to_fetch.oid, to_fetch.nr);
+	oid_array_clear(&to_fetch);
+}
+
 static int find_basename_matches(struct diff_options *options,
 				 int minimum_score,
 				 struct dir_rename_info *info,
@@ -862,18 +927,18 @@
 	int i, renames = 0;
 	struct strintmap sources;
 	struct strintmap dests;
-
-	/*
-	 * The prefeteching stuff wants to know if it can skip prefetching
-	 * blobs that are unmodified...and will then do a little extra work
-	 * to verify that the oids are indeed different before prefetching.
-	 * Unmodified blobs are only relevant when doing copy detection;
-	 * when limiting to rename detection, diffcore_rename[_extended]()
-	 * will never be called with unmodified source paths fed to us, so
-	 * the extra work necessary to check if rename_src entries are
-	 * unmodified would be a small waste.
-	 */
-	int skip_unmodified = 0;
+	struct diff_populate_filespec_options dpf_options = {
+		.check_binary = 0,
+		.missing_object_cb = NULL,
+		.missing_object_data = NULL
+	};
+	struct basename_prefetch_options prefetch_options = {
+		.repo = options->repo,
+		.relevant_sources = relevant_sources,
+		.sources = &sources,
+		.dests = &dests,
+		.info = info
+	};
 
 	/*
 	 * Create maps of basename -> fullname(s) for remaining sources and
@@ -910,6 +975,11 @@
 			strintmap_set(&dests, base, i);
 	}
 
+	if (options->repo == the_repository && has_promisor_remote()) {
+		dpf_options.missing_object_cb = basename_prefetch;
+		dpf_options.missing_object_data = &prefetch_options;
+	}
+
 	/* Now look for basename matchups and do similarity estimation */
 	for (i = 0; i < rename_src_nr; ++i) {
 		char *filename = rename_src[i].p->one->path;
@@ -953,7 +1023,7 @@
 			one = rename_src[src_index].p->one;
 			two = rename_dst[dst_index].p->two;
 			score = estimate_similarity(options->repo, one, two,
-						    minimum_score, skip_unmodified);
+						    minimum_score, &dpf_options);
 
 			/* If sufficiently similar, record as rename pair */
 			if (score < minimum_score)
@@ -1021,7 +1091,7 @@
 	 * memory for the matrix anyway.
 	 */
 	if (rename_limit <= 0)
-		rename_limit = 32767;
+		return 0; /* treat as unlimited */
 	if (st_mult(num_destinations, num_sources)
 	    <= st_mult(rename_limit, rename_limit))
 		return 0;
@@ -1272,6 +1342,14 @@
 	int num_sources, want_copies;
 	struct progress *progress = NULL;
 	struct dir_rename_info info;
+	struct diff_populate_filespec_options dpf_options = {
+		.check_binary = 0,
+		.missing_object_cb = NULL,
+		.missing_object_data = NULL
+	};
+	struct inexact_prefetch_options prefetch_options = {
+		.repo = options->repo
+	};
 
 	trace2_region_enter("diff", "setup", options->repo);
 	info.setup = 0;
@@ -1433,6 +1511,13 @@
 				(uint64_t)num_destinations * (uint64_t)num_sources);
 	}
 
+	/* Finish setting up dpf_options */
+	prefetch_options.skip_unmodified = skip_unmodified;
+	if (options->repo == the_repository && has_promisor_remote()) {
+		dpf_options.missing_object_cb = inexact_prefetch;
+		dpf_options.missing_object_data = &prefetch_options;
+	}
+
 	CALLOC_ARRAY(mx, st_mult(NUM_CANDIDATE_PER_DST, num_destinations));
 	for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
 		struct diff_filespec *two = rename_dst[i].p->two;
@@ -1458,7 +1543,7 @@
 			this_src.score = estimate_similarity(options->repo,
 							     one, two,
 							     minimum_score,
-							     skip_unmodified);
+							     &dpf_options);
 			this_src.name_score = basename_same(one, two);
 			this_src.dst = i;
 			this_src.src = j;
@@ -1543,7 +1628,7 @@
 			/* all the usual ones need to be kept */
 			diff_q(&outq, p);
 		else
-			/* no need to keep unmodified pairs; FIXME: remove earlier? */
+			/* no need to keep unmodified pairs */
 			pair_to_free = p;
 
 		if (pair_to_free)
diff --git a/dir.c b/dir.c
index ebe5ec0..23b4417 100644
--- a/dir.c
+++ b/dir.c
@@ -53,12 +53,6 @@
 	int check_only, int stop_at_first_file, const struct pathspec *pathspec);
 static int resolve_dtype(int dtype, struct index_state *istate,
 			 const char *path, int len);
-
-void dir_init(struct dir_struct *dir)
-{
-	memset(dir, 0, sizeof(*dir));
-}
-
 struct dirent *readdir_skip_dot_and_dotdot(DIR *dirp)
 {
 	struct dirent *e;
@@ -84,11 +78,21 @@
 	return ignore_case ? strcasecmp(a, b) : strcmp(a, b);
 }
 
+int fspatheq(const char *a, const char *b)
+{
+	return !fspathcmp(a, b);
+}
+
 int fspathncmp(const char *a, const char *b, size_t count)
 {
 	return ignore_case ? strncasecmp(a, b, count) : strncmp(a, b, count);
 }
 
+unsigned int fspathhash(const char *str)
+{
+	return ignore_case ? strihash(str) : strhash(str);
+}
+
 int git_fnmatch(const struct pathspec_item *item,
 		const char *pattern, const char *string,
 		int prefix)
@@ -1376,7 +1380,7 @@
 	struct path_pattern *pattern;
 	struct strbuf parent_pathname = STRBUF_INIT;
 	int result = NOT_MATCHED;
-	const char *slash_pos;
+	size_t slash_pos;
 
 	if (!pl->use_cone_patterns) {
 		pattern = last_matching_pattern_from_list(pathname, pathlen, basename,
@@ -1397,21 +1401,35 @@
 	strbuf_addch(&parent_pathname, '/');
 	strbuf_add(&parent_pathname, pathname, pathlen);
 
+	/*
+	 * Directory entries are matched if and only if a file
+	 * contained immediately within them is matched. For the
+	 * case of a directory entry, modify the path to create
+	 * a fake filename within this directory, allowing us to
+	 * use the file-base matching logic in an equivalent way.
+	 */
+	if (parent_pathname.len > 0 &&
+	    parent_pathname.buf[parent_pathname.len - 1] == '/') {
+		slash_pos = parent_pathname.len - 1;
+		strbuf_add(&parent_pathname, "-", 1);
+	} else {
+		const char *slash_ptr = strrchr(parent_pathname.buf, '/');
+		slash_pos = slash_ptr ? slash_ptr - parent_pathname.buf : 0;
+	}
+
 	if (hashmap_contains_path(&pl->recursive_hashmap,
 				  &parent_pathname)) {
 		result = MATCHED_RECURSIVE;
 		goto done;
 	}
 
-	slash_pos = strrchr(parent_pathname.buf, '/');
-
-	if (slash_pos == parent_pathname.buf) {
+	if (!slash_pos) {
 		/* include every file in root */
 		result = MATCHED;
 		goto done;
 	}
 
-	strbuf_setlen(&parent_pathname, slash_pos - parent_pathname.buf);
+	strbuf_setlen(&parent_pathname, slash_pos);
 
 	if (hashmap_contains_path(&pl->parent_hashmap, &parent_pathname)) {
 		result = MATCHED;
@@ -3105,6 +3123,7 @@
 	struct exclude_list_group *group;
 	struct pattern_list *pl;
 	struct exclude_stack *stk;
+	struct dir_struct new = DIR_INIT;
 
 	for (i = EXC_CMDL; i <= EXC_FILE; i++) {
 		group = &dir->exclude_list_group[i];
@@ -3132,7 +3151,7 @@
 	}
 	strbuf_release(&dir->basebuf);
 
-	dir_init(dir);
+	memcpy(dir, &new, sizeof(*dir));
 }
 
 struct ondisk_untracked_cache {
diff --git a/dir.h b/dir.h
index e3db9b9..b3e1a54a 100644
--- a/dir.h
+++ b/dir.h
@@ -342,6 +342,8 @@
 	unsigned visited_directories;
 };
 
+#define DIR_INIT { 0 }
+
 struct dirent *readdir_skip_dot_and_dotdot(DIR *dirp);
 
 /*Count the number of slashes for string s*/
@@ -367,8 +369,6 @@
 int report_path_error(const char *ps_matched, const struct pathspec *pathspec);
 int within_depth(const char *name, int namelen, int depth, int max_depth);
 
-void dir_init(struct dir_struct *dir);
-
 int fill_directory(struct dir_struct *dir,
 		   struct index_state *istate,
 		   const struct pathspec *pathspec);
@@ -489,7 +489,9 @@
 int remove_path(const char *path);
 
 int fspathcmp(const char *a, const char *b);
+int fspatheq(const char *a, const char *b);
 int fspathncmp(const char *a, const char *b, size_t count);
+unsigned int fspathhash(const char *str);
 
 /*
  * The prefix part of pattern must not contains wildcards.
diff --git a/entry.c b/entry.c
index 711ee06..125fabd 100644
--- a/entry.c
+++ b/entry.c
@@ -143,8 +143,8 @@
 	if (!state->delayed_checkout) {
 		state->delayed_checkout = xmalloc(sizeof(*state->delayed_checkout));
 		state->delayed_checkout->state = CE_CAN_DELAY;
-		string_list_init(&state->delayed_checkout->filters, 0);
-		string_list_init(&state->delayed_checkout->paths, 0);
+		string_list_init_nodup(&state->delayed_checkout->filters);
+		string_list_init_nodup(&state->delayed_checkout->paths);
 	}
 }
 
diff --git a/gettext.c b/gettext.c
index af2413b..bb5ba1f 100644
--- a/gettext.c
+++ b/gettext.c
@@ -66,6 +66,7 @@
 }
 
 #ifndef NO_GETTEXT
+__attribute__((format (printf, 1, 2)))
 static int test_vsnprintf(const char *fmt, ...)
 {
 	char buf[26];
diff --git a/git-compat-util.h b/git-compat-util.h
index dca72cb..b466053 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -876,6 +876,7 @@
 void *xrealloc(void *ptr, size_t size);
 void *xcalloc(size_t nmemb, size_t size);
 void *xmmap(void *start, size_t length, int prot, int flags, int fd, off_t offset);
+const char *mmap_os_err(void);
 void *xmmap_gently(void *start, size_t length, int prot, int flags, int fd, off_t offset);
 int xopen(const char *path, int flags, ...);
 ssize_t xread(int fd, void *buf, size_t len);
diff --git a/git-send-email.perl b/git-send-email.perl
index 7ba0b34..e65d969 100755
--- a/git-send-email.perl
+++ b/git-send-email.perl
@@ -18,21 +18,11 @@
 
 use 5.008;
 use strict;
-use warnings;
-use POSIX qw/strftime/;
-use Term::ReadLine;
+use warnings $ENV{GIT_PERL_FATAL_WARNINGS} ? qw(FATAL all) : ();
 use Getopt::Long;
-use Text::ParseWords;
-use Term::ANSIColor;
-use File::Temp qw/ tempdir tempfile /;
-use File::Spec::Functions qw(catdir catfile);
 use Git::LoadCPAN::Error qw(:try);
-use Cwd qw(abs_path cwd);
 use Git;
 use Git::I18N;
-use Net::Domain ();
-use Net::SMTP ();
-use Git::LoadCPAN::Mail::Address;
 
 Getopt::Long::Configure qw/ pass_through /;
 
@@ -167,7 +157,6 @@
 		       );
 }
 
-my $have_email_valid = eval { require Email::Valid; 1 };
 my $smtp;
 my $auth;
 my $num_sent = 0;
@@ -193,14 +182,6 @@
 
 my $repo = eval { Git->repository() };
 my @repo = $repo ? ($repo) : ();
-my $term = eval {
-	$ENV{"GIT_SEND_EMAIL_NOTTY"}
-		? new Term::ReadLine 'git-send-email', \*STDIN, \*STDOUT
-		: new Term::ReadLine 'git-send-email';
-};
-if ($@) {
-	$term = new FakeTerm "$@: going non-interactive";
-}
 
 # Behavior modification variables
 my ($quiet, $dry_run) = (0, 0);
@@ -289,6 +270,7 @@
 );
 
 my %config_settings = (
+    "smtpencryption" => \$smtp_encryption,
     "smtpserver" => \$smtp_server,
     "smtpserverport" => \$smtp_server_port,
     "smtpserveroption" => \@smtp_server_options,
@@ -321,9 +303,9 @@
 
 # Handle Uncouth Termination
 sub signal_handler {
-
 	# Make text normal
-	print color("reset"), "\n";
+	require Term::ANSIColor;
+	print Term::ANSIColor::color("reset"), "\n";
 
 	# SMTP password masked
 	system "stty echo";
@@ -349,11 +331,17 @@
 
 # Read our sendemail.* config
 sub read_config {
-	my ($configured, $prefix) = @_;
+	my ($known_keys, $configured, $prefix) = @_;
 
 	foreach my $setting (keys %config_bool_settings) {
 		my $target = $config_bool_settings{$setting};
-		my $v = Git::config_bool(@repo, "$prefix.$setting");
+		my $key = "$prefix.$setting";
+		next unless exists $known_keys->{$key};
+		my $v = (@{$known_keys->{$key}} == 1 &&
+			 (defined $known_keys->{$key}->[0] &&
+			  $known_keys->{$key}->[0] =~ /^(?:true|false)$/s))
+			? $known_keys->{$key}->[0] eq 'true'
+			: Git::config_bool(@repo, $key);
 		next unless defined $v;
 		next if $configured->{$setting}++;
 		$$target = $v;
@@ -361,8 +349,10 @@
 
 	foreach my $setting (keys %config_path_settings) {
 		my $target = $config_path_settings{$setting};
+		my $key = "$prefix.$setting";
+		next unless exists $known_keys->{$key};
 		if (ref($target) eq "ARRAY") {
-			my @values = Git::config_path(@repo, "$prefix.$setting");
+			my @values = Git::config_path(@repo, $key);
 			next unless @values;
 			next if $configured->{$setting}++;
 			@$target = @values;
@@ -377,36 +367,64 @@
 
 	foreach my $setting (keys %config_settings) {
 		my $target = $config_settings{$setting};
+		my $key = "$prefix.$setting";
+		next unless exists $known_keys->{$key};
 		if (ref($target) eq "ARRAY") {
-			my @values = Git::config(@repo, "$prefix.$setting");
-			next unless @values;
+			my @values = @{$known_keys->{$key}};
+			@values = grep { defined } @values;
 			next if $configured->{$setting}++;
 			@$target = @values;
 		}
 		else {
-			my $v = Git::config(@repo, "$prefix.$setting");
+			my $v = $known_keys->{$key}->[0];
 			next unless defined $v;
 			next if $configured->{$setting}++;
 			$$target = $v;
 		}
 	}
+}
 
-	if (!defined $smtp_encryption) {
-		my $setting = "$prefix.smtpencryption";
-		my $enc = Git::config(@repo, $setting);
-		return unless defined $enc;
-		return if $configured->{$setting}++;
-		if (defined $enc) {
-			$smtp_encryption = $enc;
-		} elsif (Git::config_bool(@repo, "$prefix.smtpssl")) {
-			$smtp_encryption = 'ssl';
-		}
+sub config_regexp {
+	my ($regex) = @_;
+	my @ret;
+	eval {
+		my $ret = Git::command(
+			'config',
+			'--null',
+			'--get-regexp',
+			$regex,
+		);
+		@ret = map {
+			# We must always return ($k, $v) here, since
+			# empty config values will be just "key\0",
+			# not "key\nvalue\0".
+			my ($k, $v) = split /\n/, $_, 2;
+			($k, $v);
+		} split /\0/, $ret;
+		1;
+	} or do {
+		# If we have no keys we're OK, otherwise re-throw
+		die $@ if $@->value != 1;
+	};
+	return @ret;
+}
+
+# Save ourselves a lot of work of shelling out to 'git config' (it
+# parses 'bool' etc.) by only doing so for config keys that exist.
+my %known_config_keys;
+{
+	my @kv = config_regexp("^sende?mail[.]");
+	while (my ($k, $v) = splice @kv, 0, 2) {
+		push @{$known_config_keys{$k}} => $v;
 	}
 }
 
 # sendemail.identity yields to --identity. We must parse this
 # special-case first before the rest of the config is read.
-$identity = Git::config(@repo, "sendemail.identity");
+{
+	my $key = "sendemail.identity";
+	$identity = Git::config(@repo, $key) if exists $known_config_keys{$key};
+}
 my $rc = GetOptions(
 	"identity=s" => \$identity,
 	"no-identity" => \$no_identity,
@@ -417,8 +435,8 @@
 # Now we know enough to read the config
 {
     my %configured;
-    read_config(\%configured, "sendemail.$identity") if defined $identity;
-    read_config(\%configured, "sendemail");
+    read_config(\%known_config_keys, \%configured, "sendemail.$identity") if defined $identity;
+    read_config(\%known_config_keys, \%configured, "sendemail");
 }
 
 # Begin by accumulating all the variables (defined above), that we will end up
@@ -503,7 +521,7 @@
     usage();
 }
 
-if ($forbid_sendmail_variables && (scalar Git::config_regexp("^sendmail[.]")) != 0) {
+if ($forbid_sendmail_variables && grep { /^sendmail/s } keys %known_config_keys) {
 	die __("fatal: found configuration options for 'sendmail'\n" .
 		"git-send-email is configured with the sendemail.* options - note the 'e'.\n" .
 		"Set sendemail.forbidSendmailVariables to false to disable this check.\n");
@@ -568,15 +586,27 @@
 }
 
 my ($repoauthor, $repocommitter);
-($repoauthor) = Git::ident_person(@repo, 'author');
-($repocommitter) = Git::ident_person(@repo, 'committer');
+{
+	my %cache;
+	my ($author, $committer);
+	my $common = sub {
+		my ($what) = @_;
+		return $cache{$what} if exists $cache{$what};
+		($cache{$what}) = Git::ident_person(@repo, $what);
+		return $cache{$what};
+	};
+	$repoauthor = sub { $common->('author') };
+	$repocommitter = sub { $common->('committer') };
+}
 
 sub parse_address_line {
+	require Git::LoadCPAN::Mail::Address;
 	return map { $_->format } Mail::Address->parse($_[0]);
 }
 
 sub split_addrs {
-	return quotewords('\s*,\s*', 1, @_);
+	require Text::ParseWords;
+	return Text::ParseWords::quotewords('\s*,\s*', 1, @_);
 }
 
 my %aliases;
@@ -625,10 +655,11 @@
 			s/\\"/"/g foreach @addr;
 			$aliases{$alias} = \@addr
 		}}},
-	mailrc => sub { my $fh = shift; while (<$fh>) {
+	mailrc => sub {	my $fh = shift; while (<$fh>) {
 		if (/^alias\s+(\S+)\s+(.*?)\s*$/) {
+			require Text::ParseWords;
 			# spaces delimit multiple addresses
-			$aliases{$1} = [ quotewords('\s+', 0, $2) ];
+			$aliases{$1} = [ Text::ParseWords::quotewords('\s+', 0, $2) ];
 		}}},
 	pine => sub { my $fh = shift; my $f='\t[^\t]*';
 	        for (my $x = ''; defined($x); $x = $_) {
@@ -676,7 +707,7 @@
 		if (defined($format_patch)) {
 			return $format_patch;
 		}
-		die sprintf(__ <<EOF, $f, $f);
+		die sprintf(__(<<EOF), $f, $f);
 File '%s' exists but it could also be the range of commits
 to produce patches for.  Please disambiguate by...
 
@@ -700,7 +731,8 @@
 		opendir my $dh, $f
 			or die sprintf(__("Failed to opendir %s: %s"), $f, $!);
 
-		push @files, grep { -f $_ } map { catfile($f, $_) }
+		require File::Spec;
+		push @files, grep { -f $_ } map { File::Spec->catfile($f, $_) }
 				sort readdir $dh;
 		closedir $dh;
 	} elsif ((-f $f or -p $f) and !is_format_patch_arg($f)) {
@@ -713,7 +745,8 @@
 if (@rev_list_opts) {
 	die __("Cannot run git format-patch from outside a repository\n")
 		unless $repo;
-	push @files, $repo->command('format-patch', '-o', tempdir(CLEANUP => 1), @rev_list_opts);
+	require File::Temp;
+	push @files, $repo->command('format-patch', '-o', File::Temp::tempdir(CLEANUP => 1), @rev_list_opts);
 }
 
 @files = handle_backup_files(@files);
@@ -750,19 +783,20 @@
 if ($compose) {
 	# Note that this does not need to be secure, but we will make a small
 	# effort to have it be unique
+	require File::Temp;
 	$compose_filename = ($repo ?
-		tempfile(".gitsendemail.msg.XXXXXX", DIR => $repo->repo_path()) :
-		tempfile(".gitsendemail.msg.XXXXXX", DIR => "."))[1];
+		File::Temp::tempfile(".gitsendemail.msg.XXXXXX", DIR => $repo->repo_path()) :
+		File::Temp::tempfile(".gitsendemail.msg.XXXXXX", DIR => "."))[1];
 	open my $c, ">", $compose_filename
 		or die sprintf(__("Failed to open for writing %s: %s"), $compose_filename, $!);
 
 
-	my $tpl_sender = $sender || $repoauthor || $repocommitter || '';
+	my $tpl_sender = $sender || $repoauthor->() || $repocommitter->() || '';
 	my $tpl_subject = $initial_subject || '';
 	my $tpl_in_reply_to = $initial_in_reply_to || '';
 	my $tpl_reply_to = $reply_to || '';
 
-	print $c <<EOT1, Git::prefix_lines("GIT: ", __ <<EOT2), <<EOT3;
+	print $c <<EOT1, Git::prefix_lines("GIT: ", __(<<EOT2)), <<EOT3;
 From $tpl_sender # This line is ignored.
 EOT1
 Lines beginning in "GIT:" will be removed.
@@ -859,6 +893,19 @@
 	do_edit(@files);
 }
 
+sub term {
+	my $term = eval {
+		require Term::ReadLine;
+		$ENV{"GIT_SEND_EMAIL_NOTTY"}
+			? Term::ReadLine->new('git-send-email', \*STDIN, \*STDOUT)
+			: Term::ReadLine->new('git-send-email');
+	};
+	if ($@) {
+		$term = FakeTerm->new("$@: going non-interactive");
+	}
+	return $term;
+}
+
 sub ask {
 	my ($prompt, %arg) = @_;
 	my $valid_re = $arg{valid_re};
@@ -866,6 +913,7 @@
 	my $confirm_only = $arg{confirm_only};
 	my $resp;
 	my $i = 0;
+	my $term = term();
 	return defined $default ? $default : undef
 		unless defined $term->IN and defined fileno($term->IN) and
 		       defined $term->OUT and defined fileno($term->OUT);
@@ -963,7 +1011,7 @@
 	$sender =~ s/^\s+|\s+$//g;
 	($sender) = expand_aliases($sender);
 } else {
-	$sender = $repoauthor || $repocommitter || '';
+	$sender = $repoauthor->() || $repocommitter->() || '';
 }
 
 # $sender could be an already sanitized address
@@ -1049,6 +1097,7 @@
 	return $address if ($address =~ /^($local_part_regexp)$/);
 
 	$address =~ s/^\s*<(.*)>\s*$/$1/;
+	my $have_email_valid = eval { require Email::Valid; 1 };
 	if ($have_email_valid) {
 		return scalar Email::Valid->address($address);
 	}
@@ -1108,14 +1157,15 @@
 sub make_message_id {
 	my $uniq;
 	if (!defined $message_id_stamp) {
-		$message_id_stamp = strftime("%Y%m%d%H%M%S.$$", gmtime(time));
+		require POSIX;
+		$message_id_stamp = POSIX::strftime("%Y%m%d%H%M%S.$$", gmtime(time));
 		$message_id_serial = 0;
 	}
 	$message_id_serial++;
 	$uniq = "$message_id_stamp-$message_id_serial";
 
 	my $du_part;
-	for ($sender, $repocommitter, $repoauthor) {
+	for ($sender, $repocommitter->(), $repoauthor->()) {
 		$du_part = extract_valid_address(sanitize_address($_));
 		last if (defined $du_part and $du_part ne '');
 	}
@@ -1278,6 +1328,7 @@
 sub maildomain_net {
 	my $maildomain;
 
+	require Net::Domain;
 	my $domain = Net::Domain::domainname();
 	$maildomain = $domain if valid_fqdn($domain);
 
@@ -1288,6 +1339,7 @@
 	my $maildomain;
 
 	for my $host (qw(mailhost localhost)) {
+		require Net::SMTP;
 		my $smtp = Net::SMTP->new($host);
 		if (defined $smtp) {
 			my $domain = $smtp->domain;
@@ -1980,13 +2032,15 @@
 
 	if ($repo) {
 		my $hooks_path = $repo->command_oneline('rev-parse', '--git-path', 'hooks');
-		my $validate_hook = catfile($hooks_path,
+		require File::Spec;
+		my $validate_hook = File::Spec->catfile($hooks_path,
 					    'sendemail-validate');
 		my $hook_error;
 		if (-x $validate_hook) {
-			my $target = abs_path($fn);
+			require Cwd;
+			my $target = Cwd::abs_path($fn);
 			# The hook needs a correct cwd and GIT_DIR.
-			my $cwd_save = cwd();
+			my $cwd_save = Cwd::getcwd();
 			chdir($repo->wc_path() or $repo->repo_path())
 				or die("chdir: $!");
 			local $ENV{"GIT_DIR"} = $repo->repo_path();
diff --git a/git-submodule.sh b/git-submodule.sh
index 4678378..cb06aa0 100755
--- a/git-submodule.sh
+++ b/git-submodule.sh
@@ -335,7 +335,7 @@
 		shift
 	done
 
-	git ${wt_prefix:+-C "$wt_prefix"} ${prefix:+--super-prefix "$prefix"} submodule--helper foreach ${GIT_QUIET:+--quiet} ${recursive:+--recursive} -- "$@"
+	git ${wt_prefix:+-C "$wt_prefix"} submodule--helper foreach ${GIT_QUIET:+--quiet} ${recursive:+--recursive} -- "$@"
 }
 
 #
@@ -402,7 +402,7 @@
 		shift
 	done
 
-	git ${wt_prefix:+-C "$wt_prefix"} submodule--helper deinit ${GIT_QUIET:+--quiet} ${prefix:+--prefix "$prefix"} ${force:+--force} ${deinit_all:+--all} -- "$@"
+	git ${wt_prefix:+-C "$wt_prefix"} submodule--helper deinit ${GIT_QUIET:+--quiet} ${force:+--force} ${deinit_all:+--all} -- "$@"
 }
 
 is_tip_reachable () (
@@ -726,7 +726,7 @@
 		shift
 	done
 
-	git ${wt_prefix:+-C "$wt_prefix"} ${prefix:+--super-prefix "$prefix"} submodule--helper set-branch ${GIT_QUIET:+--quiet} ${branch:+--branch "$branch"} ${default:+--default} -- "$@"
+	git ${wt_prefix:+-C "$wt_prefix"} submodule--helper set-branch ${GIT_QUIET:+--quiet} ${branch:+--branch "$branch"} ${default:+--default} -- "$@"
 }
 
 #
@@ -755,7 +755,7 @@
 		shift
 	done
 
-	git ${wt_prefix:+-C "$wt_prefix"} ${prefix:+--super-prefix "$prefix"} submodule--helper set-url ${GIT_QUIET:+--quiet} -- "$@"
+	git ${wt_prefix:+-C "$wt_prefix"} submodule--helper set-url ${GIT_QUIET:+--quiet} -- "$@"
 }
 
 #
@@ -807,7 +807,7 @@
 		shift
 	done
 
-	git ${wt_prefix:+-C "$wt_prefix"} submodule--helper summary ${prefix:+--prefix "$prefix"} ${files:+--files} ${cached:+--cached} ${for_status:+--for-status} ${summary_limit:+-n $summary_limit} -- "$@"
+	git ${wt_prefix:+-C "$wt_prefix"} submodule--helper summary ${files:+--files} ${cached:+--cached} ${for_status:+--for-status} ${summary_limit:+-n $summary_limit} -- "$@"
 }
 #
 # List all submodules, prefixed with:
@@ -848,7 +848,7 @@
 		shift
 	done
 
-	git ${wt_prefix:+-C "$wt_prefix"} ${prefix:+--super-prefix "$prefix"} submodule--helper status ${GIT_QUIET:+--quiet} ${cached:+--cached} ${recursive:+--recursive} -- "$@"
+	git ${wt_prefix:+-C "$wt_prefix"} submodule--helper status ${GIT_QUIET:+--quiet} ${cached:+--cached} ${recursive:+--recursive} -- "$@"
 }
 #
 # Sync remote urls for submodules
@@ -881,7 +881,7 @@
 		esac
 	done
 
-	git ${wt_prefix:+-C "$wt_prefix"} ${prefix:+--super-prefix "$prefix"} submodule--helper sync ${GIT_QUIET:+--quiet} ${recursive:+--recursive} -- "$@"
+	git ${wt_prefix:+-C "$wt_prefix"} submodule--helper sync ${GIT_QUIET:+--quiet} ${recursive:+--recursive} -- "$@"
 }
 
 cmd_absorbgitdirs()
diff --git a/hash.h b/hash.h
index 9c6df4d..27a1802 100644
--- a/hash.h
+++ b/hash.h
@@ -265,7 +265,7 @@
 
 /* Like oidcpy() but zero-pads the unused bytes in dst's hash array. */
 static inline void oidcpy_with_padding(struct object_id *dst,
-				       struct object_id *src)
+				       const struct object_id *src)
 {
 	size_t hashsz;
 
diff --git a/imap-send.c b/imap-send.c
index bb085d6..a0540ba 100644
--- a/imap-send.c
+++ b/imap-send.c
@@ -451,6 +451,7 @@
 	/* not reached */
 }
 
+__attribute__((format (printf, 1, 2)))
 static void imap_info(const char *msg, ...)
 {
 	va_list va;
@@ -463,6 +464,7 @@
 	}
 }
 
+__attribute__((format (printf, 1, 2)))
 static void imap_warn(const char *msg, ...)
 {
 	va_list va;
@@ -504,6 +506,7 @@
 	return ret;
 }
 
+__attribute__((format (printf, 3, 4)))
 static int nfsnprintf(char *buf, int blen, const char *fmt, ...)
 {
 	int ret;
@@ -1266,18 +1269,6 @@
 	*msg = buf;
 }
 
-#define CHUNKSIZE 0x1000
-
-static int read_message(FILE *f, struct strbuf *all_msgs)
-{
-	do {
-		if (strbuf_fread(all_msgs, CHUNKSIZE, f) <= 0)
-			break;
-	} while (!feof(f));
-
-	return ferror(f) ? -1 : 0;
-}
-
 static int count_messages(struct strbuf *all_msgs)
 {
 	int count = 0;
@@ -1582,8 +1573,8 @@
 	}
 
 	/* read the messages */
-	if (read_message(stdin, &all_msgs)) {
-		fprintf(stderr, "error reading input\n");
+	if (strbuf_read(&all_msgs, 0, 0) < 0) {
+		error_errno(_("could not read from stdin"));
 		return 1;
 	}
 
diff --git a/json-writer.c b/json-writer.c
index aadb9db..f1cfd8f 100644
--- a/json-writer.c
+++ b/json-writer.c
@@ -3,10 +3,8 @@
 
 void jw_init(struct json_writer *jw)
 {
-	strbuf_init(&jw->json, 0);
-	strbuf_init(&jw->open_stack, 0);
-	jw->need_comma = 0;
-	jw->pretty = 0;
+	struct json_writer blank = JSON_WRITER_INIT;
+	memcpy(jw, &blank, sizeof(*jw));;
 }
 
 void jw_release(struct json_writer *jw)
diff --git a/json-writer.h b/json-writer.h
index 83906b0..209355e 100644
--- a/json-writer.h
+++ b/json-writer.h
@@ -64,7 +64,10 @@
 	unsigned int pretty:1;
 };
 
-#define JSON_WRITER_INIT { STRBUF_INIT, STRBUF_INIT, 0, 0 }
+#define JSON_WRITER_INIT { \
+	.json = STRBUF_INIT, \
+	.open_stack = STRBUF_INIT, \
+}
 
 void jw_init(struct json_writer *jw);
 void jw_release(struct json_writer *jw);
diff --git a/khash.h b/khash.h
index 21c2095..cb79bf8 100644
--- a/khash.h
+++ b/khash.h
@@ -74,7 +74,7 @@
 	void kh_destroy_##name(kh_##name##_t *h);					\
 	void kh_clear_##name(kh_##name##_t *h);						\
 	khint_t kh_get_##name(const kh_##name##_t *h, khkey_t key); \
-	int kh_resize_##name(kh_##name##_t *h, khint_t new_n_buckets); \
+	void kh_resize_##name(kh_##name##_t *h, khint_t new_n_buckets); \
 	khint_t kh_put_##name(kh_##name##_t *h, khkey_t key, int *ret); \
 	void kh_del_##name(kh_##name##_t *h, khint_t x);
 
@@ -116,7 +116,7 @@
 			return __ac_iseither(h->flags, i)? h->n_buckets : i;		\
 		} else return 0;												\
 	}																	\
-	SCOPE int kh_resize_##name(kh_##name##_t *h, khint_t new_n_buckets) \
+	SCOPE void kh_resize_##name(kh_##name##_t *h, khint_t new_n_buckets) \
 	{ /* This function uses 0.25*n_buckets bytes of working space instead of [sizeof(key_t+val_t)+.25]*n_buckets. */ \
 		khint32_t *new_flags = NULL;										\
 		khint_t j = 1;													\
@@ -126,7 +126,6 @@
 			if (h->size >= (khint_t)(new_n_buckets * __ac_HASH_UPPER + 0.5)) j = 0;	/* requested size is too small */ \
 			else { /* hash table size to be changed (shrink or expand); rehash */ \
 				ALLOC_ARRAY(new_flags, __ac_fsize(new_n_buckets)); \
-				if (!new_flags) return -1;								\
 				memset(new_flags, 0xaa, __ac_fsize(new_n_buckets) * sizeof(khint32_t)); \
 				if (h->n_buckets < new_n_buckets) {	/* expand */		\
 					REALLOC_ARRAY(h->keys, new_n_buckets); \
@@ -173,18 +172,15 @@
 			h->n_occupied = h->size;									\
 			h->upper_bound = (khint_t)(h->n_buckets * __ac_HASH_UPPER + 0.5); \
 		}																\
-		return 0;														\
 	}																	\
 	SCOPE khint_t kh_put_##name(kh_##name##_t *h, khkey_t key, int *ret) \
 	{																	\
 		khint_t x;														\
 		if (h->n_occupied >= h->upper_bound) { /* update the hash table */ \
 			if (h->n_buckets > (h->size<<1)) {							\
-				if (kh_resize_##name(h, h->n_buckets - 1) < 0) { /* clear "deleted" elements */ \
-					*ret = -1; return h->n_buckets;						\
-				}														\
-			} else if (kh_resize_##name(h, h->n_buckets + 1) < 0) { /* expand the hash table */ \
-				*ret = -1; return h->n_buckets;							\
+				kh_resize_##name(h, h->n_buckets - 1); /* clear "deleted" elements */ \
+			} else { \
+				kh_resize_##name(h, h->n_buckets + 1); /* expand the hash table */ \
 			}															\
 		} /* TODO: to implement automatically shrinking; resize() already support shrinking */ \
 		{																\
diff --git a/log-tree.c b/log-tree.c
index 7b82378..6dc4412 100644
--- a/log-tree.c
+++ b/log-tree.c
@@ -134,7 +134,8 @@
 			      int flags, void *cb_data)
 {
 	struct object *obj;
-	enum decoration_type type = DECORATION_NONE;
+	enum object_type objtype;
+	enum decoration_type deco_type = DECORATION_NONE;
 	struct decoration_filter *filter = (struct decoration_filter *)cb_data;
 
 	if (filter && !ref_filter_match(refname, filter))
@@ -155,28 +156,29 @@
 		return 0;
 	}
 
-	obj = parse_object(the_repository, oid);
-	if (!obj)
+	objtype = oid_object_info(the_repository, oid, NULL);
+	if (objtype < 0)
 		return 0;
+	obj = lookup_object_by_type(the_repository, oid, objtype);
 
 	if (starts_with(refname, "refs/heads/"))
-		type = DECORATION_REF_LOCAL;
+		deco_type = DECORATION_REF_LOCAL;
 	else if (starts_with(refname, "refs/remotes/"))
-		type = DECORATION_REF_REMOTE;
+		deco_type = DECORATION_REF_REMOTE;
 	else if (starts_with(refname, "refs/tags/"))
-		type = DECORATION_REF_TAG;
+		deco_type = DECORATION_REF_TAG;
 	else if (!strcmp(refname, "refs/stash"))
-		type = DECORATION_REF_STASH;
+		deco_type = DECORATION_REF_STASH;
 	else if (!strcmp(refname, "HEAD"))
-		type = DECORATION_REF_HEAD;
+		deco_type = DECORATION_REF_HEAD;
 
-	add_name_decoration(type, refname, obj);
+	add_name_decoration(deco_type, refname, obj);
 	while (obj->type == OBJ_TAG) {
+		if (!obj->parsed)
+			parse_object(the_repository, &obj->oid);
 		obj = ((struct tag *)obj)->tagged;
 		if (!obj)
 			break;
-		if (!obj->parsed)
-			parse_object(the_repository, &obj->oid);
 		add_name_decoration(DECORATION_REF_TAG, refname, obj);
 	}
 	return 0;
diff --git a/mailmap.c b/mailmap.c
index d1f7c0d..462b395 100644
--- a/mailmap.c
+++ b/mailmap.c
@@ -8,6 +8,7 @@
 #define debug_mm(...) fprintf(stderr, __VA_ARGS__)
 #define debug_str(X) ((X) ? (X) : "(none)")
 #else
+__attribute__((format (printf, 1, 2)))
 static inline void debug_mm(const char *format, ...) {}
 static inline const char *debug_str(const char *s) { return s; }
 #endif
diff --git a/merge-ort.c b/merge-ort.c
index b954f71..ec0c590 100644
--- a/merge-ort.c
+++ b/merge-ort.c
@@ -29,6 +29,7 @@
 #include "entry.h"
 #include "ll-merge.h"
 #include "object-store.h"
+#include "promisor-remote.h"
 #include "revision.h"
 #include "strmap.h"
 #include "submodule.h"
@@ -529,6 +530,7 @@
 	renames->callback_data_nr = renames->callback_data_alloc = 0;
 }
 
+__attribute__((format (printf, 2, 3)))
 static int err(struct merge_options *opt, const char *err, ...)
 {
 	va_list params;
@@ -765,6 +767,7 @@
 	int names_idx = is_add ? side : 0;
 
 	if (is_add) {
+		assert(match_mask == 0 || match_mask == 6);
 		if (strset_contains(&renames->cached_target_names[side],
 				    pathname))
 			return;
@@ -772,6 +775,8 @@
 		unsigned content_relevant = (match_mask == 0);
 		unsigned location_relevant = (dir_rename_mask == 0x07);
 
+		assert(match_mask == 0 || match_mask == 3 || match_mask == 5);
+
 		/*
 		 * If pathname is found in cached_irrelevant[side] due to
 		 * previous pick but for this commit content is relevant,
@@ -1836,7 +1841,7 @@
 			free(new_path);
 		} else {
 			CALLOC_ARRAY(collision_info, 1);
-			string_list_init(&collision_info->source_files, 0);
+			string_list_init_nodup(&collision_info->source_files);
 			strmap_put(collisions, new_path, collision_info);
 		}
 		string_list_insert(&collision_info->source_files,
@@ -2533,7 +2538,7 @@
 	return strcmp(a->one->path, b->one->path);
 }
 
-/* Call diffcore_rename() to compute which files have changed on given side */
+/* Call diffcore_rename() to update deleted/added pairs into rename pairs */
 static void detect_regular_renames(struct merge_options *opt,
 				   unsigned side_index)
 {
@@ -2558,7 +2563,7 @@
 	diff_opts.detect_rename = DIFF_DETECT_RENAME;
 	diff_opts.rename_limit = opt->rename_limit;
 	if (opt->rename_limit <= 0)
-		diff_opts.rename_limit = 1000;
+		diff_opts.rename_limit = 7000;
 	diff_opts.rename_score = opt->rename_score;
 	diff_opts.show_rename_progress = opt->show_rename_progress;
 	diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
@@ -2586,8 +2591,10 @@
 }
 
 /*
- * Get information of all renames which occurred in 'side_pairs', discarding
- * non-renames.
+ * Get information of all renames which occurred in 'side_pairs', making use
+ * of any implicit directory renames in side_dir_renames (also making use of
+ * implicit directory renames rename_exclusions as needed by
+ * check_for_directory_rename()).  Add all (updated) renames into result.
  */
 static int collect_renames(struct merge_options *opt,
 			   struct diff_queue_struct *result,
@@ -2746,31 +2753,58 @@
 
 /*** Function Grouping: functions related to process_entries() ***/
 
-static int string_list_df_name_compare(const char *one, const char *two)
+static int sort_dirs_next_to_their_children(const char *one, const char *two)
 {
-	int onelen = strlen(one);
-	int twolen = strlen(two);
+	unsigned char c1, c2;
+
 	/*
-	 * Here we only care that entries for D/F conflicts are
-	 * adjacent, in particular with the file of the D/F conflict
-	 * appearing before files below the corresponding directory.
-	 * The order of the rest of the list is irrelevant for us.
+	 * Here we only care that entries for directories appear adjacent
+	 * to and before files underneath the directory.  We can achieve
+	 * that by pretending to add a trailing slash to every file and
+	 * then sorting.  In other words, we do not want the natural
+	 * sorting of
+	 *     foo
+	 *     foo.txt
+	 *     foo/bar
+	 * Instead, we want "foo" to sort as though it were "foo/", so that
+	 * we instead get
+	 *     foo.txt
+	 *     foo
+	 *     foo/bar
+	 * To achieve this, we basically implement our own strcmp, except that
+	 * if we get to the end of either string instead of comparing NUL to
+	 * another character, we compare '/' to it.
 	 *
-	 * To achieve this, we sort with df_name_compare and provide
-	 * the mode S_IFDIR so that D/F conflicts will sort correctly.
-	 * We use the mode S_IFDIR for everything else for simplicity,
-	 * since in other cases any changes in their order due to
-	 * sorting cause no problems for us.
+	 * If this unusual "sort as though '/' were appended" perplexes
+	 * you, perhaps it will help to note that this is not the final
+	 * sort.  write_tree() will sort again without the trailing slash
+	 * magic, but just on paths immediately under a given tree.
+	 *
+	 * The reason to not use df_name_compare directly was that it was
+	 * just too expensive (we don't have the string lengths handy), so
+	 * it was reimplemented.
 	 */
-	int cmp = df_name_compare(one, onelen, S_IFDIR,
-				  two, twolen, S_IFDIR);
+
 	/*
-	 * Now that 'foo' and 'foo/bar' compare equal, we have to make sure
-	 * that 'foo' comes before 'foo/bar'.
+	 * NOTE: This function will never be called with two equal strings,
+	 * because it is used to sort the keys of a strmap, and strmaps have
+	 * unique keys by construction.  That simplifies our c1==c2 handling
+	 * below.
 	 */
-	if (cmp)
-		return cmp;
-	return onelen - twolen;
+
+	while (*one && (*one == *two)) {
+		one++;
+		two++;
+	}
+
+	c1 = *one ? *one : '/';
+	c2 = *two ? *two : '/';
+
+	if (c1 == c2) {
+		/* Getting here means one is a leading directory of the other */
+		return (*one) ? 1 : -1;
+	} else
+		return c1 - c2;
 }
 
 static int read_oid_strbuf(struct merge_options *opt,
@@ -3237,7 +3271,7 @@
 	 *       above.
 	 */
 	if (ci->match_mask) {
-		ci->merged.clean = 1;
+		ci->merged.clean = !ci->df_conflict && !ci->path_conflict;
 		if (ci->match_mask == 6) {
 			/* stages[1] == stages[2] */
 			ci->merged.result.mode = ci->stages[1].mode;
@@ -3249,6 +3283,8 @@
 
 			ci->merged.result.mode = ci->stages[side].mode;
 			ci->merged.is_null = !ci->merged.result.mode;
+			if (ci->merged.is_null)
+				ci->merged.clean = 1;
 			oidcpy(&ci->merged.result.oid, &ci->stages[side].oid);
 
 			assert(othermask == 2 || othermask == 4);
@@ -3421,6 +3457,7 @@
 				   path)) {
 			ci->merged.is_null = 1;
 			ci->merged.clean = 1;
+			assert(!ci->df_conflict && !ci->path_conflict);
 		} else if (ci->path_conflict &&
 			   oideq(&ci->stages[0].oid, &ci->stages[side].oid)) {
 			/*
@@ -3447,6 +3484,7 @@
 		ci->merged.is_null = 1;
 		ci->merged.result.mode = 0;
 		oidcpy(&ci->merged.result.oid, null_oid());
+		assert(!ci->df_conflict);
 		ci->merged.clean = !ci->path_conflict;
 	}
 
@@ -3457,9 +3495,59 @@
 	 */
 	if (!ci->merged.clean)
 		strmap_put(&opt->priv->conflicted, path, ci);
+
+	/* Record metadata for ci->merged in dir_metadata */
 	record_entry_for_tree(dir_metadata, path, &ci->merged);
 }
 
+static void prefetch_for_content_merges(struct merge_options *opt,
+					struct string_list *plist)
+{
+	struct string_list_item *e;
+	struct oid_array to_fetch = OID_ARRAY_INIT;
+
+	if (opt->repo != the_repository || !has_promisor_remote())
+		return;
+
+	for (e = &plist->items[plist->nr-1]; e >= plist->items; --e) {
+		/* char *path = e->string; */
+		struct conflict_info *ci = e->util;
+		int i;
+
+		/* Ignore clean entries */
+		if (ci->merged.clean)
+			continue;
+
+		/* Ignore entries that don't need a content merge */
+		if (ci->match_mask || ci->filemask < 6 ||
+		    !S_ISREG(ci->stages[1].mode) ||
+		    !S_ISREG(ci->stages[2].mode) ||
+		    oideq(&ci->stages[1].oid, &ci->stages[2].oid))
+			continue;
+
+		/* Also don't need content merge if base matches either side */
+		if (ci->filemask == 7 &&
+		    S_ISREG(ci->stages[0].mode) &&
+		    (oideq(&ci->stages[0].oid, &ci->stages[1].oid) ||
+		     oideq(&ci->stages[0].oid, &ci->stages[2].oid)))
+			continue;
+
+		for (i = 0; i < 3; i++) {
+			unsigned side_mask = (1 << i);
+			struct version_info *vi = &ci->stages[i];
+
+			if ((ci->filemask & side_mask) &&
+			    S_ISREG(vi->mode) &&
+			    oid_object_info_extended(opt->repo, &vi->oid, NULL,
+						     OBJECT_INFO_FOR_PREFETCH))
+				oid_array_append(&to_fetch, &vi->oid);
+		}
+	}
+
+	promisor_remote_get_direct(opt->repo, to_fetch.oid, to_fetch.nr);
+	oid_array_clear(&to_fetch);
+}
+
 static void process_entries(struct merge_options *opt,
 			    struct object_id *result_oid)
 {
@@ -3490,7 +3578,7 @@
 	trace2_region_leave("merge", "plist copy", opt->repo);
 
 	trace2_region_enter("merge", "plist special sort", opt->repo);
-	plist.cmp = string_list_df_name_compare;
+	plist.cmp = sort_dirs_next_to_their_children;
 	string_list_sort(&plist);
 	trace2_region_leave("merge", "plist special sort", opt->repo);
 
@@ -3506,6 +3594,7 @@
 	 * the way when it is time to process the file at the same path).
 	 */
 	trace2_region_enter("merge", "processing", opt->repo);
+	prefetch_for_content_merges(opt, &plist);
 	for (entry = &plist.items[plist.nr-1]; entry >= plist.items; --entry) {
 		char *path = entry->string;
 		/*
@@ -3942,7 +4031,7 @@
 	 */
 	strmap_init_with_options(&opt->priv->paths, NULL, 0);
 	strmap_init_with_options(&opt->priv->conflicted, NULL, 0);
-	string_list_init(&opt->priv->paths_to_free, 0);
+	string_list_init_nodup(&opt->priv->paths_to_free);
 
 	/*
 	 * keys & strbufs in output will sometimes need to outlive "paths",
diff --git a/merge-recursive.c b/merge-recursive.c
index 4327e0c..7008a90 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -121,7 +121,7 @@
 	entry->dir = directory;
 	entry->non_unique_new_dir = 0;
 	strbuf_init(&entry->new_dir, 0);
-	string_list_init(&entry->possible_new_dirs, 0);
+	string_list_init_nodup(&entry->possible_new_dirs);
 }
 
 struct collision_entry {
@@ -167,6 +167,7 @@
 	}
 }
 
+__attribute__((format (printf, 2, 3)))
 static int err(struct merge_options *opt, const char *err, ...)
 {
 	va_list params;
@@ -1879,7 +1880,7 @@
 	 */
 	if (opts.detect_rename > DIFF_DETECT_RENAME)
 		opts.detect_rename = DIFF_DETECT_RENAME;
-	opts.rename_limit = (opt->rename_limit >= 0) ? opt->rename_limit : 1000;
+	opts.rename_limit = (opt->rename_limit >= 0) ? opt->rename_limit : 7000;
 	opts.rename_score = opt->rename_score;
 	opts.show_rename_progress = opt->show_rename_progress;
 	opts.output_format = DIFF_FORMAT_NO_OUTPUT;
@@ -2804,12 +2805,19 @@
 			int renamed_stage = a_renames == renames1 ? 2 : 3;
 			int other_stage =   a_renames == renames1 ? 3 : 2;
 
+			/*
+			 * Directory renames have a funny corner case...
+			 */
+			int renamed_to_self = !strcmp(ren1_src, ren1_dst);
+
 			/* BUG: We should only remove ren1_src in the base
 			 * stage and in other_stage (think of rename +
 			 * add-source case).
 			 */
-			remove_file(opt, 1, ren1_src,
-				    renamed_stage == 2 || !was_tracked(opt, ren1_src));
+			if (!renamed_to_self)
+				remove_file(opt, 1, ren1_src,
+					    renamed_stage == 2 ||
+					    !was_tracked(opt, ren1_src));
 
 			oidcpy(&src_other.oid,
 			       &ren1->src_entry->stages[other_stage].oid);
@@ -2823,6 +2831,9 @@
 			    ren1->dir_rename_original_type == 'A') {
 				setup_rename_conflict_info(RENAME_VIA_DIR,
 							   opt, ren1, NULL);
+			} else if (renamed_to_self) {
+				setup_rename_conflict_info(RENAME_NORMAL,
+							   opt, ren1, NULL);
 			} else if (oideq(&src_other.oid, null_oid())) {
 				setup_rename_conflict_info(RENAME_DELETE,
 							   opt, ren1, NULL);
@@ -3180,7 +3191,6 @@
 	struct rename *ren = ci->ren1;
 	struct merge_file_info mfi;
 	int clean;
-	int side = (ren->branch == opt->branch1 ? 2 : 3);
 
 	/* Merge the content and write it out */
 	clean = handle_content_merge(&mfi, opt, path, was_dirty(opt, path),
@@ -3190,9 +3200,7 @@
 	    opt->detect_directory_renames == MERGE_DIRECTORY_RENAMES_CONFLICT &&
 	    ren->dir_rename_original_dest) {
 		if (update_stages(opt, path,
-				  NULL,
-				  side == 2 ? &mfi.blob : NULL,
-				  side == 2 ? NULL : &mfi.blob))
+				  &mfi.blob, &mfi.blob, &mfi.blob))
 			return -1;
 		clean = 0; /* not clean, but conflicted */
 	}
@@ -3703,7 +3711,7 @@
 	}
 
 	CALLOC_ARRAY(opt->priv, 1);
-	string_list_init(&opt->priv->df_conflict_file_set, 1);
+	string_list_init_dup(&opt->priv->df_conflict_file_set);
 	return 0;
 }
 
diff --git a/merge.c b/merge.c
index 5fb88af..6e73688 100644
--- a/merge.c
+++ b/merge.c
@@ -53,7 +53,7 @@
 	struct unpack_trees_options opts;
 	struct tree_desc t[MAX_UNPACK_TREES];
 	int i, nr_trees = 0;
-	struct dir_struct dir;
+	struct dir_struct dir = DIR_INIT;
 	struct lock_file lock_file = LOCK_INIT;
 
 	refresh_index(r->index, REFRESH_QUIET, NULL, NULL, NULL);
@@ -80,7 +80,6 @@
 	}
 
 	memset(&opts, 0, sizeof(opts));
-	dir_init(&dir);
 	if (overwrite_ignore) {
 		dir.flags |= DIR_SHOW_IGNORED;
 		setup_standard_excludes(&dir);
diff --git a/midx.c b/midx.c
index 21d6a05..321c6fd 100644
--- a/midx.c
+++ b/midx.c
@@ -885,6 +885,11 @@
 static void clear_midx_files_ext(struct repository *r, const char *ext,
 				 unsigned char *keep_hash);
 
+static int midx_checksum_valid(struct multi_pack_index *m)
+{
+	return hashfile_checksum_valid(m->data, m->data_len);
+}
+
 static int write_midx_internal(const char *object_dir, struct multi_pack_index *m,
 			       struct string_list *packs_to_drop,
 			       const char *preferred_pack_name,
@@ -911,6 +916,11 @@
 	else
 		ctx.m = load_multi_pack_index(object_dir, 1);
 
+	if (ctx.m && !midx_checksum_valid(ctx.m)) {
+		warning(_("ignoring existing multi-pack-index; checksum mismatch"));
+		ctx.m = NULL;
+	}
+
 	ctx.nr = 0;
 	ctx.alloc = ctx.m ? ctx.m->num_packs : 16;
 	ctx.info = NULL;
@@ -1162,6 +1172,7 @@
 
 static int verify_midx_error;
 
+__attribute__((format (printf, 1, 2)))
 static void midx_report(const char *fmt, ...)
 {
 	va_list ap;
@@ -1218,6 +1229,9 @@
 		return result;
 	}
 
+	if (!midx_checksum_valid(m))
+		midx_report(_("incorrect checksum"));
+
 	if (flags & MIDX_PROGRESS)
 		progress = start_delayed_progress(_("Looking for referenced packfiles"),
 					  m->num_packs);
diff --git a/object-file.c b/object-file.c
index f233b44..3d27dc8 100644
--- a/object-file.c
+++ b/object-file.c
@@ -517,9 +517,9 @@
  */
 static int alt_odb_usable(struct raw_object_store *o,
 			  struct strbuf *path,
-			  const char *normalized_objdir)
+			  const char *normalized_objdir, khiter_t *pos)
 {
-	struct object_directory *odb;
+	int r;
 
 	/* Detect cases where alternate disappeared */
 	if (!is_directory(path->buf)) {
@@ -533,14 +533,20 @@
 	 * Prevent the common mistake of listing the same
 	 * thing twice, or object directory itself.
 	 */
-	for (odb = o->odb; odb; odb = odb->next) {
-		if (!fspathcmp(path->buf, odb->path))
-			return 0;
-	}
-	if (!fspathcmp(path->buf, normalized_objdir))
-		return 0;
+	if (!o->odb_by_path) {
+		khiter_t p;
 
-	return 1;
+		o->odb_by_path = kh_init_odb_path_map();
+		assert(!o->odb->next);
+		p = kh_put_odb_path_map(o->odb_by_path, o->odb->path, &r);
+		assert(r == 1); /* never used */
+		kh_value(o->odb_by_path, p) = o->odb;
+	}
+	if (fspatheq(path->buf, normalized_objdir))
+		return 0;
+	*pos = kh_put_odb_path_map(o->odb_by_path, path->buf, &r);
+	/* r: 0 = exists, 1 = never used, 2 = deleted */
+	return r == 0 ? 0 : 1;
 }
 
 /*
@@ -561,17 +567,18 @@
 static void read_info_alternates(struct repository *r,
 				 const char *relative_base,
 				 int depth);
-static int link_alt_odb_entry(struct repository *r, const char *entry,
+static int link_alt_odb_entry(struct repository *r, const struct strbuf *entry,
 	const char *relative_base, int depth, const char *normalized_objdir)
 {
 	struct object_directory *ent;
 	struct strbuf pathbuf = STRBUF_INIT;
+	khiter_t pos;
 
-	if (!is_absolute_path(entry) && relative_base) {
+	if (!is_absolute_path(entry->buf) && relative_base) {
 		strbuf_realpath(&pathbuf, relative_base, 1);
 		strbuf_addch(&pathbuf, '/');
 	}
-	strbuf_addstr(&pathbuf, entry);
+	strbuf_addbuf(&pathbuf, entry);
 
 	if (strbuf_normalize_path(&pathbuf) < 0 && relative_base) {
 		error(_("unable to normalize alternate object path: %s"),
@@ -587,23 +594,25 @@
 	while (pathbuf.len && pathbuf.buf[pathbuf.len - 1] == '/')
 		strbuf_setlen(&pathbuf, pathbuf.len - 1);
 
-	if (!alt_odb_usable(r->objects, &pathbuf, normalized_objdir)) {
+	if (!alt_odb_usable(r->objects, &pathbuf, normalized_objdir, &pos)) {
 		strbuf_release(&pathbuf);
 		return -1;
 	}
 
 	CALLOC_ARRAY(ent, 1);
-	ent->path = xstrdup(pathbuf.buf);
+	/* pathbuf.buf is already in r->objects->odb_by_path */
+	ent->path = strbuf_detach(&pathbuf, NULL);
 
 	/* add the alternate entry */
 	*r->objects->odb_tail = ent;
 	r->objects->odb_tail = &(ent->next);
 	ent->next = NULL;
+	assert(r->objects->odb_by_path);
+	kh_value(r->objects->odb_by_path, pos) = ent;
 
 	/* recursively add alternates */
-	read_info_alternates(r, pathbuf.buf, depth + 1);
+	read_info_alternates(r, ent->path, depth + 1);
 
-	strbuf_release(&pathbuf);
 	return 0;
 }
 
@@ -660,7 +669,7 @@
 		alt = parse_alt_odb_entry(alt, sep, &entry);
 		if (!entry.len)
 			continue;
-		link_alt_odb_entry(r, entry.buf,
+		link_alt_odb_entry(r, &entry,
 				   relative_base, depth, objdirbuf.buf);
 	}
 	strbuf_release(&entry);
@@ -1023,12 +1032,26 @@
 	return ret;
 }
 
+const char *mmap_os_err(void)
+{
+	static const char blank[] = "";
+#if defined(__linux__)
+	if (errno == ENOMEM) {
+		/* this continues an existing error message: */
+		static const char enomem[] =
+", check sys.vm.max_map_count and/or RLIMIT_DATA";
+		return enomem;
+	}
+#endif /* OS-specific bits */
+	return blank;
+}
+
 void *xmmap(void *start, size_t length,
 	int prot, int flags, int fd, off_t offset)
 {
 	void *ret = xmmap_gently(start, length, prot, flags, fd, offset);
 	if (ret == MAP_FAILED)
-		die_errno(_("mmap failed"));
+		die_errno(_("mmap failed%s"), mmap_os_err());
 	return ret;
 }
 
@@ -1164,7 +1187,7 @@
 
 	prepare_alt_odb(r);
 	for (odb = r->objects->odb; odb; odb = odb->next) {
-		if (oid_array_lookup(odb_loose_cache(odb, oid), oid) >= 0)
+		if (oidtree_contains(odb_loose_cache(odb, oid), oid))
 			return 1;
 	}
 	return 0;
@@ -1570,15 +1593,12 @@
 		}
 
 		/* Check if it is a missing object */
-		if (fetch_if_missing && has_promisor_remote() &&
-		    !already_retried && r == the_repository &&
+		if (fetch_if_missing && repo_has_promisor_remote(r) &&
+		    !already_retried &&
 		    !(flags & OBJECT_INFO_SKIP_FETCH_OBJECT)) {
 			/*
 			 * TODO Investigate checking promisor_remote_get_direct()
 			 * TODO return value and stopping on error here.
-			 * TODO Pass a repository struct through
-			 * promisor_remote_get_direct(), such that arbitrary
-			 * repositories work.
 			 */
 			promisor_remote_get_direct(r, real, 1);
 			already_retried = 1;
@@ -2443,39 +2463,45 @@
 static int append_loose_object(const struct object_id *oid, const char *path,
 			       void *data)
 {
-	oid_array_append(data, oid);
+	oidtree_insert(data, oid);
 	return 0;
 }
 
-struct oid_array *odb_loose_cache(struct object_directory *odb,
+struct oidtree *odb_loose_cache(struct object_directory *odb,
 				  const struct object_id *oid)
 {
 	int subdir_nr = oid->hash[0];
 	struct strbuf buf = STRBUF_INIT;
+	size_t word_bits = bitsizeof(odb->loose_objects_subdir_seen[0]);
+	size_t word_index = subdir_nr / word_bits;
+	size_t mask = 1 << (subdir_nr % word_bits);
+	uint32_t *bitmap;
 
 	if (subdir_nr < 0 ||
-	    subdir_nr >= ARRAY_SIZE(odb->loose_objects_subdir_seen))
+	    subdir_nr >= bitsizeof(odb->loose_objects_subdir_seen))
 		BUG("subdir_nr out of range");
 
-	if (odb->loose_objects_subdir_seen[subdir_nr])
-		return &odb->loose_objects_cache[subdir_nr];
-
+	bitmap = &odb->loose_objects_subdir_seen[word_index];
+	if (*bitmap & mask)
+		return odb->loose_objects_cache;
+	if (!odb->loose_objects_cache) {
+		ALLOC_ARRAY(odb->loose_objects_cache, 1);
+		oidtree_init(odb->loose_objects_cache);
+	}
 	strbuf_addstr(&buf, odb->path);
 	for_each_file_in_obj_subdir(subdir_nr, &buf,
 				    append_loose_object,
 				    NULL, NULL,
-				    &odb->loose_objects_cache[subdir_nr]);
-	odb->loose_objects_subdir_seen[subdir_nr] = 1;
+				    odb->loose_objects_cache);
+	*bitmap |= mask;
 	strbuf_release(&buf);
-	return &odb->loose_objects_cache[subdir_nr];
+	return odb->loose_objects_cache;
 }
 
 void odb_clear_loose_cache(struct object_directory *odb)
 {
-	int i;
-
-	for (i = 0; i < ARRAY_SIZE(odb->loose_objects_cache); i++)
-		oid_array_clear(&odb->loose_objects_cache[i]);
+	oidtree_clear(odb->loose_objects_cache);
+	FREE_AND_NULL(odb->loose_objects_cache);
 	memset(&odb->loose_objects_subdir_seen, 0,
 	       sizeof(odb->loose_objects_subdir_seen));
 }
diff --git a/object-name.c b/object-name.c
index 64202de..3263c19 100644
--- a/object-name.c
+++ b/object-name.c
@@ -87,27 +87,21 @@
 
 static int match_hash(unsigned, const unsigned char *, const unsigned char *);
 
+static enum cb_next match_prefix(const struct object_id *oid, void *arg)
+{
+	struct disambiguate_state *ds = arg;
+	/* no need to call match_hash, oidtree_each did prefix match */
+	update_candidates(ds, oid);
+	return ds->ambiguous ? CB_BREAK : CB_CONTINUE;
+}
+
 static void find_short_object_filename(struct disambiguate_state *ds)
 {
 	struct object_directory *odb;
 
-	for (odb = ds->repo->objects->odb; odb && !ds->ambiguous; odb = odb->next) {
-		int pos;
-		struct oid_array *loose_objects;
-
-		loose_objects = odb_loose_cache(odb, &ds->bin_pfx);
-		pos = oid_array_lookup(loose_objects, &ds->bin_pfx);
-		if (pos < 0)
-			pos = -1 - pos;
-		while (!ds->ambiguous && pos < loose_objects->nr) {
-			const struct object_id *oid;
-			oid = loose_objects->oid + pos;
-			if (!match_hash(ds->len, ds->bin_pfx.hash, oid->hash))
-				break;
-			update_candidates(ds, oid);
-			pos++;
-		}
-	}
+	for (odb = ds->repo->objects->odb; odb && !ds->ambiguous; odb = odb->next)
+		oidtree_each(odb_loose_cache(odb, &ds->bin_pfx),
+				&ds->bin_pfx, ds->len, match_prefix, ds);
 }
 
 static int match_hash(unsigned len, const unsigned char *a, const unsigned char *b)
diff --git a/object-store.h b/object-store.h
index ec32c23..e679acc 100644
--- a/object-store.h
+++ b/object-store.h
@@ -7,6 +7,9 @@
 #include "oid-array.h"
 #include "strbuf.h"
 #include "thread-utils.h"
+#include "khash.h"
+#include "dir.h"
+#include "oidtree.h"
 
 struct object_directory {
 	struct object_directory *next;
@@ -20,8 +23,8 @@
 	 *
 	 * Be sure to call odb_load_loose_cache() before using.
 	 */
-	char loose_objects_subdir_seen[256];
-	struct oid_array loose_objects_cache[256];
+	uint32_t loose_objects_subdir_seen[8]; /* 256 bits */
+	struct oidtree *loose_objects_cache;
 
 	/*
 	 * Path to the alternative object store. If this is a relative path,
@@ -30,6 +33,9 @@
 	char *path;
 };
 
+KHASH_INIT(odb_path_map, const char * /* key: odb_path */,
+	struct object_directory *, 1, fspathhash, fspatheq);
+
 void prepare_alt_odb(struct repository *r);
 char *compute_alternate_path(const char *path, struct strbuf *err);
 typedef int alt_odb_fn(struct object_directory *, void *);
@@ -54,7 +60,7 @@
  * Populate and return the loose object cache array corresponding to the
  * given object ID.
  */
-struct oid_array *odb_loose_cache(struct object_directory *odb,
+struct oidtree *odb_loose_cache(struct object_directory *odb,
 				  const struct object_id *oid);
 
 /* Empty the loose object cache for the specified object directory. */
@@ -116,6 +122,8 @@
 	 */
 	struct object_directory *odb;
 	struct object_directory **odb_tail;
+	kh_odb_path_map_t *odb_by_path;
+
 	int loaded_alternates;
 
 	/*
diff --git a/object.c b/object.c
index 1418845..4e85955 100644
--- a/object.c
+++ b/object.c
@@ -185,6 +185,24 @@
 	return obj;
 }
 
+struct object *lookup_object_by_type(struct repository *r,
+			    const struct object_id *oid,
+			    enum object_type type)
+{
+	switch (type) {
+	case OBJ_COMMIT:
+		return (struct object *)lookup_commit(r, oid);
+	case OBJ_TREE:
+		return (struct object *)lookup_tree(r, oid);
+	case OBJ_TAG:
+		return (struct object *)lookup_tag(r, oid);
+	case OBJ_BLOB:
+		return (struct object *)lookup_blob(r, oid);
+	default:
+		die("BUG: unknown object type %d", type);
+	}
+}
+
 struct object *parse_object_buffer(struct repository *r, const struct object_id *oid, enum object_type type, unsigned long size, void *buffer, int *eaten_p)
 {
 	struct object *obj;
@@ -511,6 +529,8 @@
 		free_object_directory(o->odb);
 		o->odb = next;
 	}
+	kh_destroy_odb_path_map(o->odb_by_path);
+	o->odb_by_path = NULL;
 }
 
 void raw_object_store_clear(struct raw_object_store *o)
diff --git a/object.h b/object.h
index 8bca310..3b38c9c 100644
--- a/object.h
+++ b/object.h
@@ -144,9 +144,27 @@
  */
 struct object *parse_object_buffer(struct repository *r, const struct object_id *oid, enum object_type type, unsigned long size, void *buffer, int *eaten_p);
 
-/** Returns the object, with potentially excess memory allocated. **/
+/*
+ * Allocate and return an object struct, even if you do not know the type of
+ * the object. The returned object may have its "type" field set to a real type
+ * (if somebody previously called lookup_blob(), etc), or it may be set to
+ * OBJ_NONE. In the latter case, subsequent calls to lookup_blob(), etc, will
+ * set the type field as appropriate.
+ *
+ * Use this when you do not know the expected type of an object and want to
+ * avoid parsing it for efficiency reasons. Try to avoid it otherwise; it
+ * may allocate excess memory, since the returned object must be as large as
+ * the maximum struct of any type.
+ */
 struct object *lookup_unknown_object(struct repository *r, const struct object_id *oid);
 
+/*
+ * Dispatch to the appropriate lookup_blob(), lookup_commit(), etc, based on
+ * "type".
+ */
+struct object *lookup_object_by_type(struct repository *r, const struct object_id *oid,
+				     enum object_type type);
+
 struct object_list *object_list_insert(struct object *item,
 				       struct object_list **list_p);
 
diff --git a/oidtree.c b/oidtree.c
new file mode 100644
index 0000000..7eb0e9b
--- /dev/null
+++ b/oidtree.c
@@ -0,0 +1,104 @@
+/*
+ * A wrapper around cbtree which stores oids
+ * May be used to replace oid-array for prefix (abbreviation) matches
+ */
+#include "oidtree.h"
+#include "alloc.h"
+#include "hash.h"
+
+struct oidtree_node {
+	/* n.k[] is used to store "struct object_id" */
+	struct cb_node n;
+};
+
+struct oidtree_iter_data {
+	oidtree_iter fn;
+	void *arg;
+	size_t *last_nibble_at;
+	int algo;
+	uint8_t last_byte;
+};
+
+void oidtree_init(struct oidtree *ot)
+{
+	cb_init(&ot->tree);
+	mem_pool_init(&ot->mem_pool, 0);
+}
+
+void oidtree_clear(struct oidtree *ot)
+{
+	if (ot) {
+		mem_pool_discard(&ot->mem_pool, 0);
+		oidtree_init(ot);
+	}
+}
+
+void oidtree_insert(struct oidtree *ot, const struct object_id *oid)
+{
+	struct oidtree_node *on;
+
+	if (!oid->algo)
+		BUG("oidtree_insert requires oid->algo");
+
+	on = mem_pool_alloc(&ot->mem_pool, sizeof(*on) + sizeof(*oid));
+	oidcpy_with_padding((struct object_id *)on->n.k, oid);
+
+	/*
+	 * n.b. Current callers won't get us duplicates, here.  If a
+	 * future caller causes duplicates, there'll be a a small leak
+	 * that won't be freed until oidtree_clear.  Currently it's not
+	 * worth maintaining a free list
+	 */
+	cb_insert(&ot->tree, &on->n, sizeof(*oid));
+}
+
+
+int oidtree_contains(struct oidtree *ot, const struct object_id *oid)
+{
+	struct object_id k;
+	size_t klen = sizeof(k);
+
+	oidcpy_with_padding(&k, oid);
+
+	if (oid->algo == GIT_HASH_UNKNOWN)
+		klen -= sizeof(oid->algo);
+
+	/* cb_lookup relies on memcmp on the struct, so order matters: */
+	klen += BUILD_ASSERT_OR_ZERO(offsetof(struct object_id, hash) <
+				offsetof(struct object_id, algo));
+
+	return cb_lookup(&ot->tree, (const uint8_t *)&k, klen) ? 1 : 0;
+}
+
+static enum cb_next iter(struct cb_node *n, void *arg)
+{
+	struct oidtree_iter_data *x = arg;
+	const struct object_id *oid = (const struct object_id *)n->k;
+
+	if (x->algo != GIT_HASH_UNKNOWN && x->algo != oid->algo)
+		return CB_CONTINUE;
+
+	if (x->last_nibble_at) {
+		if ((oid->hash[*x->last_nibble_at] ^ x->last_byte) & 0xf0)
+			return CB_CONTINUE;
+	}
+
+	return x->fn(oid, x->arg);
+}
+
+void oidtree_each(struct oidtree *ot, const struct object_id *oid,
+			size_t oidhexsz, oidtree_iter fn, void *arg)
+{
+	size_t klen = oidhexsz / 2;
+	struct oidtree_iter_data x = { 0 };
+	assert(oidhexsz <= GIT_MAX_HEXSZ);
+
+	x.fn = fn;
+	x.arg = arg;
+	x.algo = oid->algo;
+	if (oidhexsz & 1) {
+		x.last_byte = oid->hash[klen];
+		x.last_nibble_at = &klen;
+	}
+	cb_each(&ot->tree, (const uint8_t *)oid, klen, iter, &x);
+}
diff --git a/oidtree.h b/oidtree.h
new file mode 100644
index 0000000..77898f5
--- /dev/null
+++ b/oidtree.h
@@ -0,0 +1,22 @@
+#ifndef OIDTREE_H
+#define OIDTREE_H
+
+#include "cbtree.h"
+#include "hash.h"
+#include "mem-pool.h"
+
+struct oidtree {
+	struct cb_tree tree;
+	struct mem_pool mem_pool;
+};
+
+void oidtree_init(struct oidtree *);
+void oidtree_clear(struct oidtree *);
+void oidtree_insert(struct oidtree *, const struct object_id *);
+int oidtree_contains(struct oidtree *, const struct object_id *);
+
+typedef enum cb_next (*oidtree_iter)(const struct object_id *, void *data);
+void oidtree_each(struct oidtree *, const struct object_id *,
+			size_t oidhexsz, oidtree_iter, void *data);
+
+#endif /* OIDTREE_H */
diff --git a/pack-check.c b/pack-check.c
index 4b089fe..c8e560d 100644
--- a/pack-check.c
+++ b/pack-check.c
@@ -164,22 +164,13 @@
 
 int verify_pack_index(struct packed_git *p)
 {
-	size_t len;
-	const unsigned char *index_base;
-	git_hash_ctx ctx;
-	unsigned char hash[GIT_MAX_RAWSZ];
 	int err = 0;
 
 	if (open_pack_index(p))
 		return error("packfile %s index not opened", p->pack_name);
-	index_base = p->index_data;
-	len = p->index_size - the_hash_algo->rawsz;
 
 	/* Verify SHA1 sum of the index file */
-	the_hash_algo->init_fn(&ctx);
-	the_hash_algo->update_fn(&ctx, index_base, len);
-	the_hash_algo->final_fn(hash, &ctx);
-	if (!hasheq(hash, index_base + len))
+	if (!hashfile_checksum_valid(p->index_data, p->index_size))
 		err = error("Packfile index for %s hash mismatch",
 			    p->pack_name);
 	return err;
diff --git a/packfile.c b/packfile.c
index 755aa7a..9ef6d98 100644
--- a/packfile.c
+++ b/packfile.c
@@ -652,8 +652,8 @@
 				PROT_READ, MAP_PRIVATE,
 				p->pack_fd, win->offset);
 			if (win->base == MAP_FAILED)
-				die_errno("packfile %s cannot be mapped",
-					  p->pack_name);
+				die_errno(_("packfile %s cannot be mapped%s"),
+					  p->pack_name, mmap_os_err());
 			if (!win->offset && win->len == p->pack_size
 				&& !p->do_not_close)
 				close_pack_fd(p);
diff --git a/pathspec.h b/pathspec.h
index fceebb8..2341dc9 100644
--- a/pathspec.h
+++ b/pathspec.h
@@ -108,7 +108,7 @@
  *
  * A similar process is applied when a new pathspec magic is added. The designer
  * lifts the GUARD_PATHSPEC restriction in the functions that support the new
- * magic. At the same time (s)he has to make sure this new feature will be
+ * magic while at the same time making sure this new feature will be
  * caught at parse_pathspec() in commands that cannot handle the new magic in
  * some cases. grepping parse_pathspec() should help.
  */
diff --git a/perl/Git.pm b/perl/Git.pm
index 02eacef..090a7df 100644
--- a/perl/Git.pm
+++ b/perl/Git.pm
@@ -11,9 +11,6 @@
 use strict;
 use warnings $ENV{GIT_PERL_FATAL_WARNINGS} ? qw(FATAL all) : ();
 
-use File::Temp ();
-use File::Spec ();
-
 BEGIN {
 
 our ($VERSION, @ISA, @EXPORT, @EXPORT_OK);
@@ -103,12 +100,9 @@
 =cut
 
 
-use Carp qw(carp croak); # but croak is bad - throw instead
+sub carp { require Carp; goto &Carp::carp }
+sub croak { require Carp; goto &Carp::croak }
 use Git::LoadCPAN::Error qw(:try);
-use Cwd qw(abs_path cwd);
-use IPC::Open2 qw(open2);
-use Fcntl qw(SEEK_SET SEEK_CUR);
-use Time::Local qw(timegm);
 }
 
 
@@ -191,13 +185,15 @@
 			$dir = undef;
 		};
 
+		require Cwd;
 		if ($dir) {
+			require File::Spec;
 			File::Spec->file_name_is_absolute($dir) or $dir = $opts{Directory} . '/' . $dir;
-			$opts{Repository} = abs_path($dir);
+			$opts{Repository} = Cwd::abs_path($dir);
 
 			# If --git-dir went ok, this shouldn't die either.
 			my $prefix = $search->command_oneline('rev-parse', '--show-prefix');
-			$dir = abs_path($opts{Directory}) . '/';
+			$dir = Cwd::abs_path($opts{Directory}) . '/';
 			if ($prefix) {
 				if (substr($dir, -length($prefix)) ne $prefix) {
 					throw Error::Simple("rev-parse confused me - $dir does not have trailing $prefix");
@@ -223,7 +219,7 @@
 				throw Error::Simple("fatal: Not a git repository: $dir");
 			}
 
-			$opts{Repository} = abs_path($dir);
+			$opts{Repository} = Cwd::abs_path($dir);
 		}
 
 		delete $opts{Directory};
@@ -408,10 +404,12 @@
 	my $cwd_save = undef;
 	if ($self) {
 		shift;
-		$cwd_save = cwd();
+		require Cwd;
+		$cwd_save = Cwd::getcwd();
 		_setup_git_cmd_env($self);
 	}
-	$pid = open2($in, $out, 'git', @_);
+	require IPC::Open2;
+	$pid = IPC::Open2::open2($in, $out, 'git', @_);
 	chdir($cwd_save) if $cwd_save;
 	return ($pid, $in, $out, join(' ', @_));
 }
@@ -538,7 +536,8 @@
 	my $t = shift || time;
 	my @t = localtime($t);
 	$t[5] += 1900;
-	my $gm = timegm(@t);
+	require Time::Local;
+	my $gm = Time::Local::timegm(@t);
 	my $sign = qw( + + - )[ $gm <=> $t ];
 	return sprintf("%s%02d%02d", $sign, (gmtime(abs($t - $gm)))[2,1]);
 }
@@ -1340,6 +1339,7 @@
 		my $n = $name;
 		$n =~ s/\W/_/g; # no strange chars
 
+		require File::Temp;
 		($$temp_fd, $fname) = File::Temp::tempfile(
 			"Git_${n}_XXXXXX", UNLINK => 1, DIR => $tmpdir,
 			) or throw Error::Simple("couldn't open new temp file");
@@ -1362,9 +1362,9 @@
 
 	truncate $temp_fd, 0
 		or throw Error::Simple("couldn't truncate file");
-	sysseek($temp_fd, 0, SEEK_SET) and seek($temp_fd, 0, SEEK_SET)
+	sysseek($temp_fd, 0, Fcntl::SEEK_SET()) and seek($temp_fd, 0, Fcntl::SEEK_SET())
 		or throw Error::Simple("couldn't seek to beginning of file");
-	sysseek($temp_fd, 0, SEEK_CUR) == 0 and tell($temp_fd) == 0
+	sysseek($temp_fd, 0, Fcntl::SEEK_CUR()) == 0 and tell($temp_fd) == 0
 		or throw Error::Simple("expected file position to be reset");
 }
 
diff --git a/pkt-line.c b/pkt-line.c
index 98304ce..9f63eae 100644
--- a/pkt-line.c
+++ b/pkt-line.c
@@ -103,7 +103,7 @@
 {
 	packet_trace("0002", 4, 1);
 	if (write_in_full(fd, "0002", 4) < 0)
-		die_errno(_("unable to write stateless separator packet"));
+		die_errno(_("unable to write response end packet"));
 }
 
 int packet_flush_gently(int fd)
diff --git a/pretty.c b/pretty.c
index b1ecd03..9631529 100644
--- a/pretty.c
+++ b/pretty.c
@@ -1735,6 +1735,10 @@
 	case 'S':
 		w->source = 1;
 		break;
+	case 'd':
+	case 'D':
+		w->decorate = 1;
+		break;
 	}
 	return 0;
 }
diff --git a/pretty.h b/pretty.h
index f034609..2f16acd 100644
--- a/pretty.h
+++ b/pretty.h
@@ -65,12 +65,16 @@
 	return (fmt == CMIT_FMT_EMAIL || fmt == CMIT_FMT_MBOXRD);
 }
 
+/*
+ * Examine the user-specified format given by "fmt" (or if NULL, the global one
+ * previously saved by get_commit_format()), and set flags based on which items
+ * the format will need when it is expanded.
+ */
 struct userformat_want {
 	unsigned notes:1;
 	unsigned source:1;
+	unsigned decorate:1;
 };
-
-/* Set the flag "w->notes" if there is placeholder %N in "fmt". */
 void userformat_find_requirements(const char *fmt, struct userformat_want *w);
 
 /*
diff --git a/promisor-remote.c b/promisor-remote.c
index da3f2ca..db2ebdc 100644
--- a/promisor-remote.c
+++ b/promisor-remote.c
@@ -5,14 +5,13 @@
 #include "transport.h"
 #include "strvec.h"
 
-static char *repository_format_partial_clone;
+struct promisor_remote_config {
+	struct promisor_remote *promisors;
+	struct promisor_remote **promisors_tail;
+};
 
-void set_repository_format_partial_clone(char *partial_clone)
-{
-	repository_format_partial_clone = xstrdup_or_null(partial_clone);
-}
-
-static int fetch_objects(const char *remote_name,
+static int fetch_objects(struct repository *repo,
+			 const char *remote_name,
 			 const struct object_id *oids,
 			 int oid_nr)
 {
@@ -22,6 +21,8 @@
 
 	child.git_cmd = 1;
 	child.in = -1;
+	if (repo != the_repository)
+		prepare_other_repo_env(&child.env_array, repo->gitdir);
 	strvec_pushl(&child.args, "-c", "fetch.negotiationAlgorithm=noop",
 		     "fetch", remote_name, "--no-tags",
 		     "--no-write-fetch-head", "--recurse-submodules=no",
@@ -30,6 +31,8 @@
 		die(_("promisor-remote: unable to fork off fetch subprocess"));
 	child_in = xfdopen(child.in, "w");
 
+	trace2_data_intmax("promisor", repo, "fetch_count", oid_nr);
+
 	for (i = 0; i < oid_nr; i++) {
 		if (fputs(oid_to_hex(&oids[i]), child_in) < 0)
 			die_errno(_("promisor-remote: could not write to fetch subprocess"));
@@ -42,10 +45,8 @@
 	return finish_command(&child) ? -1 : 0;
 }
 
-static struct promisor_remote *promisors;
-static struct promisor_remote **promisors_tail = &promisors;
-
-static struct promisor_remote *promisor_remote_new(const char *remote_name)
+static struct promisor_remote *promisor_remote_new(struct promisor_remote_config *config,
+						   const char *remote_name)
 {
 	struct promisor_remote *r;
 
@@ -57,18 +58,19 @@
 
 	FLEX_ALLOC_STR(r, name, remote_name);
 
-	*promisors_tail = r;
-	promisors_tail = &r->next;
+	*config->promisors_tail = r;
+	config->promisors_tail = &r->next;
 
 	return r;
 }
 
-static struct promisor_remote *promisor_remote_lookup(const char *remote_name,
+static struct promisor_remote *promisor_remote_lookup(struct promisor_remote_config *config,
+						      const char *remote_name,
 						      struct promisor_remote **previous)
 {
 	struct promisor_remote *r, *p;
 
-	for (p = NULL, r = promisors; r; p = r, r = r->next)
+	for (p = NULL, r = config->promisors; r; p = r, r = r->next)
 		if (!strcmp(r->name, remote_name)) {
 			if (previous)
 				*previous = p;
@@ -78,7 +80,8 @@
 	return NULL;
 }
 
-static void promisor_remote_move_to_tail(struct promisor_remote *r,
+static void promisor_remote_move_to_tail(struct promisor_remote_config *config,
+					 struct promisor_remote *r,
 					 struct promisor_remote *previous)
 {
 	if (r->next == NULL)
@@ -87,14 +90,15 @@
 	if (previous)
 		previous->next = r->next;
 	else
-		promisors = r->next ? r->next : r;
+		config->promisors = r->next ? r->next : r;
 	r->next = NULL;
-	*promisors_tail = r;
-	promisors_tail = &r->next;
+	*config->promisors_tail = r;
+	config->promisors_tail = &r->next;
 }
 
 static int promisor_remote_config(const char *var, const char *value, void *data)
 {
+	struct promisor_remote_config *config = data;
 	const char *name;
 	size_t namelen;
 	const char *subkey;
@@ -110,8 +114,8 @@
 
 		remote_name = xmemdupz(name, namelen);
 
-		if (!promisor_remote_lookup(remote_name, NULL))
-			promisor_remote_new(remote_name);
+		if (!promisor_remote_lookup(config, remote_name, NULL))
+			promisor_remote_new(config, remote_name);
 
 		free(remote_name);
 		return 0;
@@ -120,9 +124,9 @@
 		struct promisor_remote *r;
 		char *remote_name = xmemdupz(name, namelen);
 
-		r = promisor_remote_lookup(remote_name, NULL);
+		r = promisor_remote_lookup(config, remote_name, NULL);
 		if (!r)
-			r = promisor_remote_new(remote_name);
+			r = promisor_remote_new(config, remote_name);
 
 		free(remote_name);
 
@@ -135,59 +139,63 @@
 	return 0;
 }
 
-static int initialized;
-
-static void promisor_remote_init(void)
+static void promisor_remote_init(struct repository *r)
 {
-	if (initialized)
+	struct promisor_remote_config *config;
+
+	if (r->promisor_remote_config)
 		return;
-	initialized = 1;
+	config = r->promisor_remote_config =
+		xcalloc(sizeof(*r->promisor_remote_config), 1);
+	config->promisors_tail = &config->promisors;
 
-	git_config(promisor_remote_config, NULL);
+	repo_config(r, promisor_remote_config, config);
 
-	if (repository_format_partial_clone) {
+	if (r->repository_format_partial_clone) {
 		struct promisor_remote *o, *previous;
 
-		o = promisor_remote_lookup(repository_format_partial_clone,
+		o = promisor_remote_lookup(config,
+					   r->repository_format_partial_clone,
 					   &previous);
 		if (o)
-			promisor_remote_move_to_tail(o, previous);
+			promisor_remote_move_to_tail(config, o, previous);
 		else
-			promisor_remote_new(repository_format_partial_clone);
+			promisor_remote_new(config, r->repository_format_partial_clone);
 	}
 }
 
-static void promisor_remote_clear(void)
+void promisor_remote_clear(struct promisor_remote_config *config)
 {
-	while (promisors) {
-		struct promisor_remote *r = promisors;
-		promisors = promisors->next;
+	while (config->promisors) {
+		struct promisor_remote *r = config->promisors;
+		config->promisors = config->promisors->next;
 		free(r);
 	}
 
-	promisors_tail = &promisors;
+	config->promisors_tail = &config->promisors;
 }
 
-void promisor_remote_reinit(void)
+void repo_promisor_remote_reinit(struct repository *r)
 {
-	initialized = 0;
-	promisor_remote_clear();
-	promisor_remote_init();
+	promisor_remote_clear(r->promisor_remote_config);
+	FREE_AND_NULL(r->promisor_remote_config);
+	promisor_remote_init(r);
 }
 
-struct promisor_remote *promisor_remote_find(const char *remote_name)
+struct promisor_remote *repo_promisor_remote_find(struct repository *r,
+						  const char *remote_name)
 {
-	promisor_remote_init();
+	promisor_remote_init(r);
 
 	if (!remote_name)
-		return promisors;
+		return r->promisor_remote_config->promisors;
 
-	return promisor_remote_lookup(remote_name, NULL);
+	return promisor_remote_lookup(r->promisor_remote_config, remote_name, NULL);
 }
 
-int has_promisor_remote(void)
+int repo_has_promisor_remote(struct repository *r)
 {
-	return !!promisor_remote_find(NULL);
+	return !!repo_promisor_remote_find(r, NULL);
 }
 
 static int remove_fetched_oids(struct repository *repo,
@@ -235,10 +243,10 @@
 	if (oid_nr == 0)
 		return 0;
 
-	promisor_remote_init();
+	promisor_remote_init(repo);
 
-	for (r = promisors; r; r = r->next) {
-		if (fetch_objects(r->name, remaining_oids, remaining_nr) < 0) {
+	for (r = repo->promisor_remote_config->promisors; r; r = r->next) {
+		if (fetch_objects(repo, r->name, remaining_oids, remaining_nr) < 0) {
 			if (remaining_nr == 1)
 				continue;
 			remaining_nr = remove_fetched_oids(repo, &remaining_oids,
diff --git a/promisor-remote.h b/promisor-remote.h
index c7a1406..edc45ab 100644
--- a/promisor-remote.h
+++ b/promisor-remote.h
@@ -17,9 +17,25 @@
 	const char name[FLEX_ARRAY];
 };
 
-void promisor_remote_reinit(void);
-struct promisor_remote *promisor_remote_find(const char *remote_name);
-int has_promisor_remote(void);
+void repo_promisor_remote_reinit(struct repository *r);
+static inline void promisor_remote_reinit(void)
+{
+	repo_promisor_remote_reinit(the_repository);
+}
+
+void promisor_remote_clear(struct promisor_remote_config *config);
+
+struct promisor_remote *repo_promisor_remote_find(struct repository *r, const char *remote_name);
+static inline struct promisor_remote *promisor_remote_find(const char *remote_name)
+{
+	return repo_promisor_remote_find(the_repository, remote_name);
+}
+
+int repo_has_promisor_remote(struct repository *r);
+static inline int has_promisor_remote(void)
+{
+	return repo_has_promisor_remote(the_repository);
+}
 
 /*
  * Fetches all requested objects from all promisor remotes, trying them one at
@@ -32,10 +48,4 @@
 			       const struct object_id *oids,
 			       int oid_nr);
 
-/*
- * This should be used only once from setup.c to set the value we got
- * from the extensions.partialclone config option.
- */
-void set_repository_format_partial_clone(char *partial_clone);
-
 #endif /* PROMISOR_REMOTE_H */
diff --git a/quote.h b/quote.h
index 768cc63..049d8dd 100644
--- a/quote.h
+++ b/quote.h
@@ -31,6 +31,7 @@
 
 void sq_quote_buf(struct strbuf *, const char *src);
 void sq_quote_argv(struct strbuf *, const char **argv);
+__attribute__((format (printf, 2, 3)))
 void sq_quotef(struct strbuf *, const char *fmt, ...);
 
 /*
diff --git a/reachable.c b/reachable.c
index c598472..84e3d0d 100644
--- a/reachable.c
+++ b/reachable.c
@@ -159,24 +159,6 @@
 				      FOR_EACH_OBJECT_LOCAL_ONLY);
 }
 
-static void *lookup_object_by_type(struct repository *r,
-				   const struct object_id *oid,
-				   enum object_type type)
-{
-	switch (type) {
-	case OBJ_COMMIT:
-		return lookup_commit(r, oid);
-	case OBJ_TREE:
-		return lookup_tree(r, oid);
-	case OBJ_TAG:
-		return lookup_tag(r, oid);
-	case OBJ_BLOB:
-		return lookup_blob(r, oid);
-	default:
-		die("BUG: unknown object type %d", type);
-	}
-}
-
 static int mark_object_seen(const struct object_id *oid,
 			     enum object_type type,
 			     int exclude,
diff --git a/read-cache.c b/read-cache.c
index 0c3ac3c..46ccd66 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -1585,8 +1585,7 @@
 	 */
 	preload_index(istate, pathspec, 0);
 	trace2_region_enter("index", "refresh", NULL);
-	/* TODO: audit for interaction with sparse-index. */
-	ensure_full_index(istate);
+
 	for (i = 0; i < istate->cache_nr; i++) {
 		struct cache_entry *ce, *new_entry;
 		int cache_errno = 0;
@@ -1601,6 +1600,13 @@
 		if (ignore_skip_worktree && ce_skip_worktree(ce))
 			continue;
 
+		/*
+		 * If this entry is a sparse directory, then there isn't
+		 * any stat() information to update. Ignore the entry.
+		 */
+		if (S_ISSPARSEDIR(ce->ce_mode))
+			continue;
+
 		if (pathspec && !ce_path_match(istate, ce, pathspec, seen))
 			filtered = 1;
 
@@ -2233,7 +2239,8 @@
 
 	mmap = xmmap_gently(NULL, mmap_size, PROT_READ, MAP_PRIVATE, fd, 0);
 	if (mmap == MAP_FAILED)
-		die_errno(_("%s: unable to map index file"), path);
+		die_errno(_("%s: unable to map index file%s"), path,
+			mmap_os_err());
 	close(fd);
 
 	hdr = (const struct cache_header *)mmap;
diff --git a/ref-filter.c b/ref-filter.c
index 4db0e40..f45d3a1 100644
--- a/ref-filter.c
+++ b/ref-filter.c
@@ -213,6 +213,7 @@
  * Expand string, append it to strbuf *sb, then return error code ret.
  * Allow to save few lines of code.
  */
+__attribute__((format (printf, 3, 4)))
 static int strbuf_addf_ret(struct strbuf *sb, int ret, const char *fmt, ...)
 {
 	va_list ap;
diff --git a/refs.c b/refs.c
index 8c94902..8b9f7c3 100644
--- a/refs.c
+++ b/refs.c
@@ -2010,7 +2010,7 @@
 	     oideq(current_ref_iter->oid, base)))
 		return ref_iterator_peel(current_ref_iter, peeled);
 
-	return peel_object(base, peeled);
+	return peel_object(base, peeled) ? -1 : 0;
 }
 
 int refs_create_symref(struct ref_store *refs,
diff --git a/refs/packed-backend.c b/refs/packed-backend.c
index dfecdbc..f8aa97d 100644
--- a/refs/packed-backend.c
+++ b/refs/packed-backend.c
@@ -889,7 +889,7 @@
 	} else if ((iter->base.flags & (REF_ISBROKEN | REF_ISSYMREF))) {
 		return -1;
 	} else {
-		return !!peel_object(&iter->oid, peeled);
+		return peel_object(&iter->oid, peeled) ? -1 : 0;
 	}
 }
 
@@ -1425,7 +1425,7 @@
 	 */
 
 	CALLOC_ARRAY(data, 1);
-	string_list_init(&data->updates, 0);
+	string_list_init_nodup(&data->updates);
 
 	transaction->backend_data = data;
 
diff --git a/refs/ref-cache.c b/refs/ref-cache.c
index 46f1e54..49d732f 100644
--- a/refs/ref-cache.c
+++ b/refs/ref-cache.c
@@ -491,7 +491,7 @@
 static int cache_ref_iterator_peel(struct ref_iterator *ref_iterator,
 				   struct object_id *peeled)
 {
-	return peel_object(ref_iterator->oid, peeled);
+	return peel_object(ref_iterator->oid, peeled) ? -1 : 0;
 }
 
 static int cache_ref_iterator_abort(struct ref_iterator *ref_iterator)
diff --git a/refs/refs-internal.h b/refs/refs-internal.h
index 467f4b3..3155708 100644
--- a/refs/refs-internal.h
+++ b/refs/refs-internal.h
@@ -453,6 +453,9 @@
  */
 typedef int ref_iterator_advance_fn(struct ref_iterator *ref_iterator);
 
+/*
+ * Peels the current ref, returning 0 for success or -1 for failure.
+ */
 typedef int ref_iterator_peel_fn(struct ref_iterator *ref_iterator,
 				 struct object_id *peeled);
 
diff --git a/remote-curl.c b/remote-curl.c
index 9d432c2..6c320d5 100644
--- a/remote-curl.c
+++ b/remote-curl.c
@@ -653,7 +653,7 @@
 			memcpy(buf - 4, "0000", 4);
 			break;
 		case PACKET_READ_RESPONSE_END:
-			die(_("remote server sent stateless separator"));
+			die(_("remote server sent unexpected response end packet"));
 		}
 	}
 
diff --git a/repository.c b/repository.c
index 448cd55..b2bf44c 100644
--- a/repository.c
+++ b/repository.c
@@ -11,6 +11,7 @@
 #include "lockfile.h"
 #include "submodule-config.h"
 #include "sparse-index.h"
+#include "promisor-remote.h"
 
 /* The main repository */
 static struct repository the_repo;
@@ -172,6 +173,10 @@
 
 	repo_set_hash_algo(repo, format.hash_algo);
 
+	/* take ownership of format.partial_clone */
+	repo->repository_format_partial_clone = format.partial_clone;
+	format.partial_clone = NULL;
+
 	if (worktree)
 		repo_set_worktree(repo, worktree);
 
@@ -258,6 +263,11 @@
 		if (repo->index != &the_index)
 			FREE_AND_NULL(repo->index);
 	}
+
+	if (repo->promisor_remote_config) {
+		promisor_remote_clear(repo->promisor_remote_config);
+		FREE_AND_NULL(repo->promisor_remote_config);
+	}
 }
 
 int repo_read_index(struct repository *repo)
diff --git a/repository.h b/repository.h
index a45f752..3740c93 100644
--- a/repository.h
+++ b/repository.h
@@ -10,6 +10,7 @@
 struct pathspec;
 struct raw_object_store;
 struct submodule_cache;
+struct promisor_remote_config;
 
 enum untracked_cache_setting {
 	UNTRACKED_CACHE_UNSET = -1,
@@ -139,6 +140,10 @@
 	/* True if commit-graph has been disabled within this process. */
 	int commit_graph_disabled;
 
+	/* Configurations related to promisor remotes. */
+	char *repository_format_partial_clone;
+	struct promisor_remote_config *promisor_remote_config;
+
 	/* Configurations */
 
 	/* Indicate if a repository has a different 'commondir' from 'gitdir' */
diff --git a/revision.h b/revision.h
index 5c5510d..fbb068d 100644
--- a/revision.h
+++ b/revision.h
@@ -215,7 +215,8 @@
 			missing_newline:1,
 			date_mode_explicit:1,
 			preserve_subject:1,
-			encode_email_headers:1;
+			encode_email_headers:1,
+			include_header:1;
 	unsigned int	disable_stdin:1;
 	/* --show-linear-break */
 	unsigned int	track_linear:1,
diff --git a/run-command.c b/run-command.c
index be6bc12..f72e72c 100644
--- a/run-command.c
+++ b/run-command.c
@@ -11,9 +11,8 @@
 
 void child_process_init(struct child_process *child)
 {
-	memset(child, 0, sizeof(*child));
-	strvec_init(&child->args);
-	strvec_init(&child->env_array);
+	struct child_process blank = CHILD_PROCESS_INIT;
+	memcpy(child, &blank, sizeof(*child));
 }
 
 void child_process_clear(struct child_process *child)
@@ -1892,3 +1891,15 @@
 
 	return run_command(&maint);
 }
+
+void prepare_other_repo_env(struct strvec *env_array, const char *new_git_dir)
+{
+	const char * const *var;
+
+	for (var = local_repo_env; *var; var++) {
+		if (strcmp(*var, CONFIG_DATA_ENVIRONMENT) &&
+		    strcmp(*var, CONFIG_COUNT_ENVIRONMENT))
+			strvec_push(env_array, *var);
+	}
+	strvec_pushf(env_array, "%s=%s", GIT_DIR_ENVIRONMENT, new_git_dir);
+}
diff --git a/run-command.h b/run-command.h
index d08414a..af12967 100644
--- a/run-command.h
+++ b/run-command.h
@@ -141,7 +141,10 @@
 	void *clean_on_exit_handler_cbdata;
 };
 
-#define CHILD_PROCESS_INIT { NULL, STRVEC_INIT, STRVEC_INIT }
+#define CHILD_PROCESS_INIT { \
+	.args = STRVEC_INIT, \
+	.env_array = STRVEC_INIT, \
+}
 
 /**
  * The functions: child_process_init, start_command, finish_command,
@@ -483,4 +486,14 @@
 			       task_finished_fn, void *pp_cb,
 			       const char *tr2_category, const char *tr2_label);
 
+/**
+ * Convenience function which prepares env_array for a command to be run in a
+ * new repo. This adds all GIT_* environment variables to env_array with the
+ * exception of GIT_CONFIG_PARAMETERS and GIT_CONFIG_COUNT (which cause the
+ * corresponding environment variables to be unset in the subprocess) and adds
+ * an environment variable pointing to new_git_dir. See local_repo_env in
+ * cache.h for more information.
+ */
+void prepare_other_repo_env(struct strvec *env_array, const char *new_git_dir);
+
 #endif
diff --git a/send-pack.c b/send-pack.c
index 9cb9f71..5a79e0e 100644
--- a/send-pack.c
+++ b/send-pack.c
@@ -486,6 +486,12 @@
 	const char *push_cert_nonce = NULL;
 	struct packet_reader reader;
 
+	if (!remote_refs) {
+		fprintf(stderr, "No refs in common and none specified; doing nothing.\n"
+			"Perhaps you should specify a branch.\n");
+		return 0;
+	}
+
 	git_config_get_bool("push.negotiate", &push_negotiate);
 	if (push_negotiate)
 		get_commons_through_negotiation(args->url, remote_refs, &commons);
@@ -534,11 +540,6 @@
 		}
 	}
 
-	if (!remote_refs) {
-		fprintf(stderr, "No refs in common and none specified; doing nothing.\n"
-			"Perhaps you should specify a branch.\n");
-		return 0;
-	}
 	if (args->atomic && !atomic_supported)
 		die(_("the receiving end does not support --atomic push"));
 
diff --git a/sequencer.c b/sequencer.c
index 0bec01c..7f07cd0 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -3521,6 +3521,7 @@
 	return status;
 }
 
+__attribute__((format (printf, 2, 3)))
 static int safe_append(const char *filename, const char *fmt, ...)
 {
 	va_list ap;
@@ -3598,8 +3599,27 @@
 	return ret;
 }
 
+__attribute__((format (printf, 3, 4)))
 static const char *reflog_message(struct replay_opts *opts,
-	const char *sub_action, const char *fmt, ...);
+	const char *sub_action, const char *fmt, ...)
+{
+	va_list ap;
+	static struct strbuf buf = STRBUF_INIT;
+	char *reflog_action = getenv(GIT_REFLOG_ACTION);
+
+	va_start(ap, fmt);
+	strbuf_reset(&buf);
+	strbuf_addstr(&buf, reflog_action ? reflog_action : action_name(opts));
+	if (sub_action)
+		strbuf_addf(&buf, " (%s)", sub_action);
+	if (fmt) {
+		strbuf_addstr(&buf, ": ");
+		strbuf_vaddf(&buf, fmt, ap);
+	}
+	va_end(ap);
+
+	return buf.buf;
+}
 
 static int do_reset(struct repository *r,
 		    const char *name, int len,
@@ -4178,27 +4198,6 @@
 	return apply_save_autostash_oid(stash_oid, 1);
 }
 
-static const char *reflog_message(struct replay_opts *opts,
-	const char *sub_action, const char *fmt, ...)
-{
-	va_list ap;
-	static struct strbuf buf = STRBUF_INIT;
-	char *reflog_action = getenv(GIT_REFLOG_ACTION);
-
-	va_start(ap, fmt);
-	strbuf_reset(&buf);
-	strbuf_addstr(&buf, reflog_action ? reflog_action : action_name(opts));
-	if (sub_action)
-		strbuf_addf(&buf, " (%s)", sub_action);
-	if (fmt) {
-		strbuf_addstr(&buf, ": ");
-		strbuf_vaddf(&buf, fmt, ap);
-	}
-	va_end(ap);
-
-	return buf.buf;
-}
-
 static int run_git_checkout(struct repository *r, struct replay_opts *opts,
 			    const char *commit, const char *action)
 {
diff --git a/serve.c b/serve.c
index aa8209f..f11c0e0 100644
--- a/serve.c
+++ b/serve.c
@@ -258,7 +258,7 @@
 			state = PROCESS_REQUEST_DONE;
 			break;
 		case PACKET_READ_RESPONSE_END:
-			BUG("unexpected stateless separator packet");
+			BUG("unexpected response end packet");
 		}
 	}
 
diff --git a/server-info.c b/server-info.c
index de0aa44..7701d7c 100644
--- a/server-info.c
+++ b/server-info.c
@@ -27,6 +27,7 @@
 	return uic->old_fp == NULL;
 }
 
+__attribute__((format (printf, 2, 3)))
 static int uic_printf(struct update_info_ctx *uic, const char *fmt, ...)
 {
 	va_list ap;
diff --git a/setup.c b/setup.c
index ead2f80..eb9367c 100644
--- a/setup.c
+++ b/setup.c
@@ -468,8 +468,6 @@
 			data->precious_objects = git_config_bool(var, value);
 			return EXTENSION_OK;
 		} else if (!strcmp(ext, "partialclone")) {
-			if (!value)
-				return config_error_nonbool(var);
 			data->partial_clone = xstrdup(value);
 			return EXTENSION_OK;
 		} else if (!strcmp(ext, "worktreeconfig")) {
@@ -566,7 +564,6 @@
 	}
 
 	repository_format_precious_objects = candidate->precious_objects;
-	set_repository_format_partial_clone(candidate->partial_clone);
 	repository_format_worktree_config = candidate->worktree_config;
 	string_list_clear(&candidate->unknown_extensions, 0);
 	string_list_clear(&candidate->v1_only_extensions, 0);
@@ -1197,6 +1194,11 @@
 		return -1;
 	}
 
+	/* take ownership of candidate.partial_clone */
+	the_repository->repository_format_partial_clone =
+		candidate.partial_clone;
+	candidate.partial_clone = NULL;
+
 	clear_repository_format(&candidate);
 	return 0;
 }
@@ -1304,8 +1306,13 @@
 				gitdir = DEFAULT_GIT_DIR_ENVIRONMENT;
 			setup_git_env(gitdir);
 		}
-		if (startup_info->have_repository)
+		if (startup_info->have_repository) {
 			repo_set_hash_algo(the_repository, repo_fmt.hash_algo);
+			/* take ownership of repo_fmt.partial_clone */
+			the_repository->repository_format_partial_clone =
+				repo_fmt.partial_clone;
+			repo_fmt.partial_clone = NULL;
+		}
 	}
 	/*
 	 * Since precompose_string_if_needed() needs to look at
@@ -1390,6 +1397,8 @@
 	check_repository_format_gently(get_git_dir(), fmt, NULL);
 	startup_info->have_repository = 1;
 	repo_set_hash_algo(the_repository, fmt->hash_algo);
+	the_repository->repository_format_partial_clone =
+		xstrdup_or_null(fmt->partial_clone);
 	clear_repository_format(&repo_fmt);
 }
 
diff --git a/sparse-index.c b/sparse-index.c
index affc404..53c8f71 100644
--- a/sparse-index.c
+++ b/sparse-index.c
@@ -116,6 +116,17 @@
 	return res;
 }
 
+static int index_has_unmerged_entries(struct index_state *istate)
+{
+	int i;
+	for (i = 0; i < istate->cache_nr; i++) {
+		if (ce_stage(istate->cache[i]))
+			return 1;
+	}
+
+	return 0;
+}
+
 int convert_to_sparse(struct index_state *istate)
 {
 	int test_env;
@@ -152,6 +163,13 @@
 		return -1;
 	}
 
+	/*
+	 * NEEDSWORK: If we have unmerged entries, then stay full.
+	 * Unmerged entries prevent the cache-tree extension from working.
+	 */
+	if (index_has_unmerged_entries(istate))
+		return 0;
+
 	if (cache_tree_update(istate, 0)) {
 		warning(_("unable to update cache-tree, staying full"));
 		return -1;
@@ -168,6 +186,10 @@
 	cache_tree_free(&istate->cache_tree);
 	cache_tree_update(istate, 0);
 
+	istate->fsmonitor_has_run_once = 0;
+	FREE_AND_NULL(istate->fsmonitor_dirty);
+	FREE_AND_NULL(istate->fsmonitor_last_update);
+
 	istate->sparse_index = 1;
 	trace2_region_leave("index", "convert_to_sparse", istate->repo);
 	return 0;
@@ -195,7 +217,7 @@
 	strbuf_addstr(base, path);
 
 	ce = make_cache_entry(istate, mode, oid, base->buf, 0, 0);
-	ce->ce_flags |= CE_SKIP_WORKTREE;
+	ce->ce_flags |= CE_SKIP_WORKTREE | CE_EXTENDED;
 	set_index_entry(istate, istate->cache_nr++, ce);
 
 	strbuf_setlen(base, len);
@@ -264,6 +286,9 @@
 	istate->cache = full->cache;
 	istate->cache_nr = full->cache_nr;
 	istate->cache_alloc = full->cache_alloc;
+	istate->fsmonitor_has_run_once = 0;
+	FREE_AND_NULL(istate->fsmonitor_dirty);
+	FREE_AND_NULL(istate->fsmonitor_last_update);
 
 	strbuf_release(&base);
 	free(full);
diff --git a/strbuf.c b/strbuf.c
index 4df30b4..c8a5789 100644
--- a/strbuf.c
+++ b/strbuf.c
@@ -52,8 +52,8 @@
 
 void strbuf_init(struct strbuf *sb, size_t hint)
 {
-	sb->alloc = sb->len = 0;
-	sb->buf = strbuf_slopbuf;
+	struct strbuf blank = STRBUF_INIT;
+	memcpy(sb, &blank, sizeof(*sb));
 	if (hint)
 		strbuf_grow(sb, hint);
 }
diff --git a/strbuf.h b/strbuf.h
index 223ee20..5b1113a 100644
--- a/strbuf.h
+++ b/strbuf.h
@@ -263,6 +263,7 @@
 void strbuf_vinsertf(struct strbuf *sb, size_t pos, const char *fmt,
 		     va_list ap);
 
+__attribute__((format (printf, 3, 4)))
 void strbuf_insertf(struct strbuf *sb, size_t pos, const char *fmt, ...);
 
 /**
@@ -337,8 +338,8 @@
  * placeholder is unknown, then the percent sign is copied, too.
  *
  * In order to facilitate caching and to make it possible to give
- * parameters to the callback, `strbuf_expand()` passes a context pointer,
- * which can be used by the programmer of the callback as she sees fit.
+ * parameters to the callback, `strbuf_expand()` passes a context
+ * pointer with any kind of data.
  */
 typedef size_t (*expand_fn_t) (struct strbuf *sb,
 			       const char *placeholder,
diff --git a/string-list.c b/string-list.c
index a917955..43576ad 100644
--- a/string-list.c
+++ b/string-list.c
@@ -1,10 +1,24 @@
 #include "cache.h"
 #include "string-list.h"
 
+void string_list_init_nodup(struct string_list *list)
+{
+	struct string_list blank = STRING_LIST_INIT_NODUP;
+	memcpy(list, &blank, sizeof(*list));
+}
+
+void string_list_init_dup(struct string_list *list)
+{
+	struct string_list blank = STRING_LIST_INIT_DUP;
+	memcpy(list, &blank, sizeof(*list));
+}
+
 void string_list_init(struct string_list *list, int strdup_strings)
 {
-	memset(list, 0, sizeof(*list));
-	list->strdup_strings = strdup_strings;
+	if (strdup_strings)
+		string_list_init_dup(list);
+	else
+		string_list_init_nodup(list);
 }
 
 /* if there is no exact match, point to the index where the entry could be
diff --git a/string-list.h b/string-list.h
index 6c5d274..0d6b469 100644
--- a/string-list.h
+++ b/string-list.h
@@ -91,14 +91,21 @@
 	compare_strings_fn cmp; /* NULL uses strcmp() */
 };
 
-#define STRING_LIST_INIT_NODUP { NULL, 0, 0, 0, NULL }
-#define STRING_LIST_INIT_DUP   { NULL, 0, 0, 1, NULL }
+#define STRING_LIST_INIT_NODUP { 0 }
+#define STRING_LIST_INIT_DUP   { .strdup_strings = 1 }
 
 /* General functions which work with both sorted and unsorted lists. */
 
 /**
- * Initialize the members of the string_list, set `strdup_strings`
- * member according to the value of the second parameter.
+ * Initialize the members of a string_list pointer in the same way as
+ * the corresponding `STRING_LIST_INIT_NODUP` and
+ * `STRING_LIST_INIT_DUP` macros.
+ */
+void string_list_init_nodup(struct string_list *list);
+void string_list_init_dup(struct string_list *list);
+
+/**
+ * TODO remove: For compatibility with any in-flight older API users
  */
 void string_list_init(struct string_list *list, int strdup_strings);
 
diff --git a/strmap.c b/strmap.c
index 4fb9f61..ee48635 100644
--- a/strmap.c
+++ b/strmap.c
@@ -25,7 +25,8 @@
 
 void strmap_init(struct strmap *map)
 {
-	strmap_init_with_options(map, NULL, 1);
+	struct strmap blank = STRMAP_INIT;
+	memcpy(map, &blank, sizeof(*map));
 }
 
 void strmap_init_with_options(struct strmap *map,
diff --git a/strvec.c b/strvec.c
index 21dce0a..61a76ce 100644
--- a/strvec.c
+++ b/strvec.c
@@ -6,9 +6,8 @@
 
 void strvec_init(struct strvec *array)
 {
-	array->v = empty_strvec;
-	array->nr = 0;
-	array->alloc = 0;
+	struct strvec blank = STRVEC_INIT;
+	memcpy(array, &blank, sizeof(*array));
 }
 
 static void strvec_push_nodup(struct strvec *array, const char *value)
diff --git a/submodule.c b/submodule.c
index 0b1d9c1..8e611fe 100644
--- a/submodule.c
+++ b/submodule.c
@@ -484,27 +484,14 @@
 	strbuf_release(&sb);
 }
 
-static void prepare_submodule_repo_env_no_git_dir(struct strvec *out)
-{
-	const char * const *var;
-
-	for (var = local_repo_env; *var; var++) {
-		if (strcmp(*var, CONFIG_DATA_ENVIRONMENT))
-			strvec_push(out, *var);
-	}
-}
-
 void prepare_submodule_repo_env(struct strvec *out)
 {
-	prepare_submodule_repo_env_no_git_dir(out);
-	strvec_pushf(out, "%s=%s", GIT_DIR_ENVIRONMENT,
-		     DEFAULT_GIT_DIR_ENVIRONMENT);
+	prepare_other_repo_env(out, DEFAULT_GIT_DIR_ENVIRONMENT);
 }
 
 static void prepare_submodule_repo_env_in_gitdir(struct strvec *out)
 {
-	prepare_submodule_repo_env_no_git_dir(out);
-	strvec_pushf(out, "%s=.", GIT_DIR_ENVIRONMENT);
+	prepare_other_repo_env(out, ".");
 }
 
 /*
diff --git a/t/helper/test-advise.c b/t/helper/test-advise.c
index a7043df..cb88113 100644
--- a/t/helper/test-advise.c
+++ b/t/helper/test-advise.c
@@ -16,7 +16,7 @@
 	 * selected here and in t0018 where this command is being
 	 * executed.
 	 */
-	advise_if_enabled(ADVICE_NESTED_TAG, argv[1]);
+	advise_if_enabled(ADVICE_NESTED_TAG, "%s", argv[1]);
 
 	return 0;
 }
diff --git a/t/helper/test-oidtree.c b/t/helper/test-oidtree.c
new file mode 100644
index 0000000..180ee28
--- /dev/null
+++ b/t/helper/test-oidtree.c
@@ -0,0 +1,49 @@
+#include "test-tool.h"
+#include "cache.h"
+#include "oidtree.h"
+
+static enum cb_next print_oid(const struct object_id *oid, void *data)
+{
+	puts(oid_to_hex(oid));
+	return CB_CONTINUE;
+}
+
+int cmd__oidtree(int argc, const char **argv)
+{
+	struct oidtree ot;
+	struct strbuf line = STRBUF_INIT;
+	int nongit_ok;
+	int algo = GIT_HASH_UNKNOWN;
+
+	oidtree_init(&ot);
+	setup_git_directory_gently(&nongit_ok);
+
+	while (strbuf_getline(&line, stdin) != EOF) {
+		const char *arg;
+		struct object_id oid;
+
+		if (skip_prefix(line.buf, "insert ", &arg)) {
+			if (get_oid_hex_any(arg, &oid) == GIT_HASH_UNKNOWN)
+				die("insert not a hexadecimal oid: %s", arg);
+			algo = oid.algo;
+			oidtree_insert(&ot, &oid);
+		} else if (skip_prefix(line.buf, "contains ", &arg)) {
+			if (get_oid_hex(arg, &oid))
+				die("contains not a hexadecimal oid: %s", arg);
+			printf("%d\n", oidtree_contains(&ot, &oid));
+		} else if (skip_prefix(line.buf, "each ", &arg)) {
+			char buf[GIT_MAX_HEXSZ + 1] = { '0' };
+			memset(&oid, 0, sizeof(oid));
+			memcpy(buf, arg, strlen(arg));
+			buf[hash_algos[algo].hexsz] = '\0';
+			get_oid_hex_any(buf, &oid);
+			oid.algo = algo;
+			oidtree_each(&ot, &oid, strlen(arg), print_oid, NULL);
+		} else if (!strcmp(line.buf, "clear")) {
+			oidtree_clear(&ot);
+		} else {
+			die("unknown command: %s", line.buf);
+		}
+	}
+	return 0;
+}
diff --git a/t/helper/test-partial-clone.c b/t/helper/test-partial-clone.c
new file mode 100644
index 0000000..3f102cf
--- /dev/null
+++ b/t/helper/test-partial-clone.c
@@ -0,0 +1,43 @@
+#include "cache.h"
+#include "test-tool.h"
+#include "repository.h"
+#include "object-store.h"
+
+/*
+ * Prints the size of the object corresponding to the given hash in a specific
+ * gitdir. This is similar to "git -C gitdir cat-file -s", except that this
+ * exercises the code that accesses the object of an arbitrary repository that
+ * is not the_repository. ("git -C gitdir" makes it so that the_repository is
+ * the one in gitdir.)
+ */
+static void object_info(const char *gitdir, const char *oid_hex)
+{
+	struct repository r;
+	struct object_id oid;
+	unsigned long size;
+	struct object_info oi = {.sizep = &size};
+	const char *p;
+
+	if (repo_init(&r, gitdir, NULL))
+		die("could not init repo");
+	if (parse_oid_hex(oid_hex, &oid, &p))
+		die("could not parse oid");
+	if (oid_object_info_extended(&r, &oid, &oi, 0))
+		die("could not obtain object info");
+	printf("%d\n", (int) size);
+}
+
+int cmd__partial_clone(int argc, const char **argv)
+{
+	setup_git_directory();
+
+	if (argc < 4)
+		die("too few arguments");
+
+	if (!strcmp(argv[1], "object-info"))
+		object_info(argv[2], argv[3]);
+	else
+		die("invalid argument '%s'", argv[1]);
+
+	return 0;
+}
diff --git a/t/helper/test-pkt-line.c b/t/helper/test-pkt-line.c
index 5e638f0..c5e052e 100644
--- a/t/helper/test-pkt-line.c
+++ b/t/helper/test-pkt-line.c
@@ -26,6 +26,16 @@
 	}
 }
 
+static void pack_raw_stdin(void)
+{
+	struct strbuf sb = STRBUF_INIT;
+
+	if (strbuf_read(&sb, 0, 0) < 0)
+		die_errno("failed to read from stdin");
+	packet_write(1, sb.buf, sb.len);
+	strbuf_release(&sb);
+}
+
 static void unpack(void)
 {
 	struct packet_reader reader;
@@ -110,6 +120,8 @@
 
 	if (!strcmp(argv[1], "pack"))
 		pack(argc - 2, argv + 2);
+	else if (!strcmp(argv[1], "pack-raw-stdin"))
+		pack_raw_stdin();
 	else if (!strcmp(argv[1], "unpack"))
 		unpack();
 	else if (!strcmp(argv[1], "unpack-sideband"))
diff --git a/t/helper/test-tool.c b/t/helper/test-tool.c
index c5bd0c6..490ac02 100644
--- a/t/helper/test-tool.c
+++ b/t/helper/test-tool.c
@@ -43,9 +43,11 @@
 	{ "mktemp", cmd__mktemp },
 	{ "oid-array", cmd__oid_array },
 	{ "oidmap", cmd__oidmap },
+	{ "oidtree", cmd__oidtree },
 	{ "online-cpus", cmd__online_cpus },
 	{ "parse-options", cmd__parse_options },
 	{ "parse-pathspec-file", cmd__parse_pathspec_file },
+	{ "partial-clone", cmd__partial_clone },
 	{ "path-utils", cmd__path_utils },
 	{ "pcre2-config", cmd__pcre2_config },
 	{ "pkt-line", cmd__pkt_line },
diff --git a/t/helper/test-tool.h b/t/helper/test-tool.h
index e8069a3..f8dc266 100644
--- a/t/helper/test-tool.h
+++ b/t/helper/test-tool.h
@@ -32,9 +32,11 @@
 int cmd__mergesort(int argc, const char **argv);
 int cmd__mktemp(int argc, const char **argv);
 int cmd__oidmap(int argc, const char **argv);
+int cmd__oidtree(int argc, const char **argv);
 int cmd__online_cpus(int argc, const char **argv);
 int cmd__parse_options(int argc, const char **argv);
 int cmd__parse_pathspec_file(int argc, const char** argv);
+int cmd__partial_clone(int argc, const char **argv);
 int cmd__path_utils(int argc, const char **argv);
 int cmd__pcre2_config(int argc, const char **argv);
 int cmd__pkt_line(int argc, const char **argv);
diff --git a/t/t0000-basic.sh b/t/t0000-basic.sh
index 2c6e34b..f68c27d 100755
--- a/t/t0000-basic.sh
+++ b/t/t0000-basic.sh
@@ -69,6 +69,23 @@
 _run_sub_test_lib_test_common () {
 	neg="$1" name="$2" descr="$3" # stdin is the body of the test code
 	shift 3
+
+	# intercept pseudo-options at the front of the argument list that we
+	# will not pass to child script
+	skip=
+	while test $# -gt 0
+	do
+		case "$1" in
+		--skip=*)
+			skip=${1#--*=}
+			shift
+			;;
+		*)
+			break
+			;;
+		esac
+	done
+
 	mkdir "$name" &&
 	(
 		# Pretend we're not running under a test harness, whether we
@@ -91,6 +108,8 @@
 		export TEST_DIRECTORY &&
 		TEST_OUTPUT_DIRECTORY=$(pwd) &&
 		export TEST_OUTPUT_DIRECTORY &&
+		GIT_SKIP_TESTS=$skip &&
+		export GIT_SKIP_TESTS &&
 		sane_unset GIT_TEST_FAIL_PREREQS &&
 		if test -z "$neg"
 		then
@@ -319,9 +338,9 @@
 
 test_expect_success 'GIT_SKIP_TESTS' '
 	(
-		GIT_SKIP_TESTS="git.2" && export GIT_SKIP_TESTS &&
 		run_sub_test_lib_test git-skip-tests-basic \
-			"GIT_SKIP_TESTS" <<-\EOF &&
+			"GIT_SKIP_TESTS" \
+			--skip="git.2" <<-\EOF &&
 		for i in 1 2 3
 		do
 			test_expect_success "passing test #$i" "true"
@@ -340,9 +359,9 @@
 
 test_expect_success 'GIT_SKIP_TESTS several tests' '
 	(
-		GIT_SKIP_TESTS="git.2 git.5" && export GIT_SKIP_TESTS &&
 		run_sub_test_lib_test git-skip-tests-several \
-			"GIT_SKIP_TESTS several tests" <<-\EOF &&
+			"GIT_SKIP_TESTS several tests" \
+			--skip="git.2 git.5" <<-\EOF &&
 		for i in 1 2 3 4 5 6
 		do
 			test_expect_success "passing test #$i" "true"
@@ -364,9 +383,9 @@
 
 test_expect_success 'GIT_SKIP_TESTS sh pattern' '
 	(
-		GIT_SKIP_TESTS="git.[2-5]" && export GIT_SKIP_TESTS &&
 		run_sub_test_lib_test git-skip-tests-sh-pattern \
-			"GIT_SKIP_TESTS sh pattern" <<-\EOF &&
+			"GIT_SKIP_TESTS sh pattern" \
+			--skip="git.[2-5]" <<-\EOF &&
 		for i in 1 2 3 4 5 6
 		do
 			test_expect_success "passing test #$i" "true"
@@ -388,9 +407,9 @@
 
 test_expect_success 'GIT_SKIP_TESTS entire suite' '
 	(
-		GIT_SKIP_TESTS="git" && export GIT_SKIP_TESTS &&
 		run_sub_test_lib_test git-skip-tests-entire-suite \
-			"GIT_SKIP_TESTS entire suite" <<-\EOF &&
+			"GIT_SKIP_TESTS entire suite" \
+			--skip="git" <<-\EOF &&
 		for i in 1 2 3
 		do
 			test_expect_success "passing test #$i" "true"
@@ -405,9 +424,9 @@
 
 test_expect_success 'GIT_SKIP_TESTS does not skip unmatched suite' '
 	(
-		GIT_SKIP_TESTS="notgit" && export GIT_SKIP_TESTS &&
 		run_sub_test_lib_test git-skip-tests-unmatched-suite \
-			"GIT_SKIP_TESTS does not skip unmatched suite" <<-\EOF &&
+			"GIT_SKIP_TESTS does not skip unmatched suite" \
+			--skip="notgit" <<-\EOF &&
 		for i in 1 2 3
 		do
 			test_expect_success "passing test #$i" "true"
diff --git a/t/t0069-oidtree.sh b/t/t0069-oidtree.sh
new file mode 100755
index 0000000..bfb1397
--- /dev/null
+++ b/t/t0069-oidtree.sh
@@ -0,0 +1,49 @@
+#!/bin/sh
+
+test_description='basic tests for the oidtree implementation'
+. ./test-lib.sh
+
+maxhexsz=$(test_oid hexsz)
+echoid () {
+	prefix="${1:+$1 }"
+	shift
+	while test $# -gt 0
+	do
+		shortoid="$1"
+		shift
+		difference=$(($maxhexsz - ${#shortoid}))
+		printf "%s%s%0${difference}d\\n" "$prefix" "$shortoid" "0"
+	done
+}
+
+test_expect_success 'oidtree insert and contains' '
+	cat >expect <<-\EOF &&
+		0
+		0
+		0
+		1
+		1
+		0
+	EOF
+	{
+		echoid insert 444 1 2 3 4 5 a b c d e &&
+		echoid contains 44 441 440 444 4440 4444
+		echo clear
+	} | test-tool oidtree >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'oidtree each' '
+	echoid "" 123 321 321 >expect &&
+	{
+		echoid insert f 9 8 123 321 a b c d e
+		echo each 12300
+		echo each 3211
+		echo each 3210
+		echo each 32100
+		echo clear
+	} | test-tool oidtree >actual &&
+	test_cmp expect actual
+'
+
+test_done
diff --git a/t/t0410-partial-clone.sh b/t/t0410-partial-clone.sh
index 584a039..a211a66 100755
--- a/t/t0410-partial-clone.sh
+++ b/t/t0410-partial-clone.sh
@@ -604,6 +604,29 @@
 	git -C repo cherry-pick side1
 '
 
+test_expect_success 'lazy-fetch when accessing object not in the_repository' '
+	rm -rf full partial.git &&
+	test_create_repo full &&
+	test_commit -C full create-a-file file.txt &&
+
+	test_config -C full uploadpack.allowfilter 1 &&
+	test_config -C full uploadpack.allowanysha1inwant 1 &&
+	git clone --filter=blob:none --bare "file://$(pwd)/full" partial.git &&
+	FILE_HASH=$(git -C full rev-parse HEAD:file.txt) &&
+
+	# Sanity check that the file is missing
+	git -C partial.git rev-list --objects --missing=print HEAD >out &&
+	grep "[?]$FILE_HASH" out &&
+
+	git -C full cat-file -s "$FILE_HASH" >expect &&
+	test-tool partial-clone object-info partial.git "$FILE_HASH" >actual &&
+	test_cmp expect actual &&
+
+	# Sanity check that the file is now present
+	git -C partial.git rev-list --objects --missing=print HEAD >out &&
+	! grep "[?]$FILE_HASH" out
+'
+
 . "$TEST_DIRECTORY"/lib-httpd.sh
 start_httpd
 
diff --git a/t/t1092-sparse-checkout-compatibility.sh b/t/t1092-sparse-checkout-compatibility.sh
index d028b73..cabbd42 100755
--- a/t/t1092-sparse-checkout-compatibility.sh
+++ b/t/t1092-sparse-checkout-compatibility.sh
@@ -17,7 +17,7 @@
 		echo "after folder1" >g &&
 		echo "after x" >z &&
 		mkdir folder1 folder2 deep x &&
-		mkdir deep/deeper1 deep/deeper2 &&
+		mkdir deep/deeper1 deep/deeper2 deep/before deep/later &&
 		mkdir deep/deeper1/deepest &&
 		echo "after deeper1" >deep/e &&
 		echo "after deepest" >deep/deeper1/e &&
@@ -25,10 +25,23 @@
 		cp a folder2 &&
 		cp a x &&
 		cp a deep &&
+		cp a deep/before &&
 		cp a deep/deeper1 &&
 		cp a deep/deeper2 &&
+		cp a deep/later &&
 		cp a deep/deeper1/deepest &&
 		cp -r deep/deeper1/deepest deep/deeper2 &&
+		mkdir deep/deeper1/0 &&
+		mkdir deep/deeper1/0/0 &&
+		touch deep/deeper1/0/1 &&
+		touch deep/deeper1/0/0/0 &&
+		>folder1- &&
+		>folder1.x &&
+		>folder10 &&
+		cp -r deep/deeper1/0 folder1 &&
+		cp -r deep/deeper1/0 folder2 &&
+		echo >>folder1/0/0/0 &&
+		echo >>folder2/0/1 &&
 		git add . &&
 		git commit -m "initial commit" &&
 		git checkout -b base &&
@@ -40,7 +53,7 @@
 		done &&
 
 		git checkout -b rename-base base &&
-		echo >folder1/larger-content <<-\EOF &&
+		cat >folder1/larger-content <<-\EOF &&
 		matching
 		lines
 		help
@@ -56,11 +69,17 @@
 		mv folder1/a folder2/b &&
 		mv folder1/larger-content folder2/edited-content &&
 		echo >>folder2/edited-content &&
+		echo >>folder2/0/1 &&
+		echo stuff >>deep/deeper1/a &&
 		git add . &&
 		git commit -m "rename folder1/... to folder2/..." &&
 
 		git checkout -b rename-out-to-in rename-base &&
 		mv folder1/a deep/deeper1/b &&
+		echo more stuff >>deep/deeper1/a &&
+		rm folder2/0/1 &&
+		mkdir folder2/0/1 &&
+		echo >>folder2/0/1/1 &&
 		mv folder1/larger-content deep/deeper1/edited-content &&
 		echo >>deep/deeper1/edited-content &&
 		git add . &&
@@ -68,6 +87,9 @@
 
 		git checkout -b rename-in-to-out rename-base &&
 		mv deep/deeper1/a folder1/b &&
+		echo >>folder2/0/1 &&
+		rm -rf folder1/0/0 &&
+		echo >>folder1/0/0 &&
 		mv deep/deeper1/larger-content folder1/edited-content &&
 		echo >>folder1/edited-content &&
 		git add . &&
@@ -196,6 +218,14 @@
 	test_all_match git status --porcelain=v2 -uno
 '
 
+test_expect_success 'status reports sparse-checkout' '
+	init_repos &&
+	git -C sparse-checkout status >full &&
+	git -C sparse-index status >sparse &&
+	test_i18ngrep "You are in a sparse checkout with " full &&
+	test_i18ngrep "You are in a sparse checkout." sparse
+'
+
 test_expect_success 'add, commit, checkout' '
 	init_repos &&
 
@@ -232,6 +262,44 @@
 	test_all_match git checkout -
 '
 
+test_expect_success 'status/add: outside sparse cone' '
+	init_repos &&
+
+	# adding a "missing" file outside the cone should fail
+	test_sparse_match test_must_fail git add folder1/a &&
+
+	# folder1 is at HEAD, but outside the sparse cone
+	run_on_sparse mkdir folder1 &&
+	cp initial-repo/folder1/a sparse-checkout/folder1/a &&
+	cp initial-repo/folder1/a sparse-index/folder1/a &&
+
+	test_sparse_match git status &&
+
+	write_script edit-contents <<-\EOF &&
+	echo text >>$1
+	EOF
+	run_on_sparse ../edit-contents folder1/a &&
+	run_on_all ../edit-contents folder1/new &&
+
+	test_sparse_match git status --porcelain=v2 &&
+
+	# This "git add folder1/a" fails with a warning
+	# in the sparse repos, differing from the full
+	# repo. This is intentional.
+	test_sparse_match test_must_fail git add folder1/a &&
+	test_sparse_match test_must_fail git add --refresh folder1/a &&
+	test_all_match git status --porcelain=v2 &&
+
+	test_all_match git add . &&
+	test_all_match git status --porcelain=v2 &&
+	test_all_match git commit -m folder1/new &&
+
+	run_on_all ../edit-contents folder1/newer &&
+	test_all_match git add folder1/ &&
+	test_all_match git status --porcelain=v2 &&
+	test_all_match git commit -m folder1/newer
+'
+
 test_expect_success 'checkout and reset --hard' '
 	init_repos &&
 
@@ -262,13 +330,29 @@
 	test_all_match git diff --staged
 '
 
-test_expect_success 'diff with renames' '
+test_expect_success 'diff with renames and conflicts' '
 	init_repos &&
 
 	for branch in rename-out-to-out rename-out-to-in rename-in-to-out
 	do
 		test_all_match git checkout rename-base &&
 		test_all_match git checkout $branch -- . &&
+		test_all_match git status --porcelain=v2 &&
+		test_all_match git diff --staged --no-renames &&
+		test_all_match git diff --staged --find-renames || return 1
+	done
+'
+
+test_expect_success 'diff with directory/file conflicts' '
+	init_repos &&
+
+	for branch in rename-out-to-out rename-out-to-in rename-in-to-out
+	do
+		git -C full-checkout reset --hard &&
+		test_sparse_match git reset --hard &&
+		test_all_match git checkout $branch &&
+		test_all_match git checkout rename-base -- . &&
+		test_all_match git status --porcelain=v2 &&
 		test_all_match git diff --staged --no-renames &&
 		test_all_match git diff --staged --find-renames || return 1
 	done
@@ -308,8 +392,8 @@
 	test_all_match git blame deep/deeper2/deepest/a
 '
 
-# TODO: reset currently does not behave as expected when in a
-# sparse-checkout.
+# NEEDSWORK: a sparse-checkout behaves differently from a full checkout
+# in this scenario, but it shouldn't.
 test_expect_failure 'checkout and reset (mixed)' '
 	init_repos &&
 
@@ -319,8 +403,8 @@
 	test_all_match git reset update-folder2
 '
 
-# Ensure that sparse-index behaves identically to
-# sparse-checkout with a full index.
+# NEEDSWORK: a sparse-checkout behaves differently from a full checkout
+# in this scenario, but it shouldn't.
 test_expect_success 'checkout and reset (mixed) [sparse]' '
 	init_repos &&
 
@@ -352,6 +436,28 @@
 	done
 '
 
+# Sparse-index fails to convert the index in the
+# final 'git cherry-pick' command.
+test_expect_success 'cherry-pick with conflicts' '
+	init_repos &&
+
+	write_script edit-conflict <<-\EOF &&
+	echo $1 >conflict
+	EOF
+
+	test_all_match git checkout -b to-cherry-pick &&
+	run_on_all ../edit-conflict ABC &&
+	test_all_match git add conflict &&
+	test_all_match git commit -m "conflict to pick" &&
+
+	test_all_match git checkout -B base HEAD~1 &&
+	run_on_all ../edit-conflict DEF &&
+	test_all_match git add conflict &&
+	test_all_match git commit -m "conflict in base" &&
+
+	test_all_match test_must_fail git cherry-pick to-cherry-pick
+'
+
 test_expect_success 'clean' '
 	init_repos &&
 
@@ -405,12 +511,52 @@
 	GIT_TRACE2_EVENT="$(pwd)/trace2.txt" GIT_TRACE2_EVENT_NESTING=10 \
 		git -C sparse-index -c core.fsmonitor="" reset --hard &&
 	test_region index convert_to_sparse trace2.txt &&
-	test_region index ensure_full_index trace2.txt &&
-
-	rm trace2.txt &&
-	GIT_TRACE2_EVENT="$(pwd)/trace2.txt" GIT_TRACE2_EVENT_NESTING=10 \
-		git -C sparse-index -c core.fsmonitor="" status -uno &&
 	test_region index ensure_full_index trace2.txt
 '
 
+test_expect_success 'sparse-index is not expanded' '
+	init_repos &&
+
+	rm -f trace2.txt &&
+	echo >>sparse-index/untracked.txt &&
+	GIT_TRACE2_EVENT="$(pwd)/trace2.txt" GIT_TRACE2_EVENT_NESTING=10 \
+		git -C sparse-index status &&
+	test_region ! index ensure_full_index trace2.txt
+'
+
+# NEEDSWORK: a sparse-checkout behaves differently from a full checkout
+# in this scenario, but it shouldn't.
+test_expect_success 'reset mixed and checkout orphan' '
+	init_repos &&
+
+	test_all_match git checkout rename-out-to-in &&
+
+	# Sparse checkouts do not agree with full checkouts about
+	# how to report a directory/file conflict during a reset.
+	# This command would fail with test_all_match because the
+	# full checkout reports "T folder1/0/1" while a sparse
+	# checkout reports "D folder1/0/1". This matches because
+	# the sparse checkouts skip "adding" the other side of
+	# the conflict.
+	test_sparse_match git reset --mixed HEAD~1 &&
+	test_sparse_match test-tool read-cache --table --expand &&
+	test_sparse_match git status --porcelain=v2 &&
+
+	# At this point, sparse-checkouts behave differently
+	# from the full-checkout.
+	test_sparse_match git checkout --orphan new-branch &&
+	test_sparse_match test-tool read-cache --table --expand &&
+	test_sparse_match git status --porcelain=v2
+'
+
+test_expect_success 'add everything with deep new file' '
+	init_repos &&
+
+	run_on_sparse git sparse-checkout set deep/deeper1/deepest &&
+
+	run_on_all touch deep/deeper1/x &&
+	test_all_match git add . &&
+	test_all_match git status --porcelain=v2
+'
+
 test_done
diff --git a/t/t1415-worktree-refs.sh b/t/t1415-worktree-refs.sh
index 66f27d0..a3e6ea0 100755
--- a/t/t1415-worktree-refs.sh
+++ b/t/t1415-worktree-refs.sh
@@ -40,9 +40,8 @@
 '
 
 test_expect_success 'ambiguous main-worktree/HEAD' '
-	mkdir -p .git/refs/heads/main-worktree &&
-	test_when_finished rm -f .git/refs/heads/main-worktree/HEAD &&
-	cp .git/HEAD .git/refs/heads/main-worktree/HEAD &&
+	test_when_finished git update-ref -d refs/heads/main-worktree/HEAD &&
+	git update-ref refs/heads/main-worktree/HEAD $(git rev-parse HEAD) &&
 	git rev-parse main-worktree/HEAD 2>warn &&
 	grep "main-worktree/HEAD.*ambiguous" warn
 '
@@ -54,9 +53,8 @@
 '
 
 test_expect_success 'ambiguous worktrees/xx/HEAD' '
-	mkdir -p .git/refs/heads/worktrees/wt1 &&
-	test_when_finished rm -f .git/refs/heads/worktrees/wt1/HEAD &&
-	cp .git/HEAD .git/refs/heads/worktrees/wt1/HEAD &&
+	git update-ref refs/heads/worktrees/wt1/HEAD $(git rev-parse HEAD) &&
+	test_when_finished git update-ref -d refs/heads/worktrees/wt1/HEAD &&
 	git rev-parse worktrees/wt1/HEAD 2>warn &&
 	grep "worktrees/wt1/HEAD.*ambiguous" warn
 '
diff --git a/t/t2400-worktree-add.sh b/t/t2400-worktree-add.sh
index 96dfca1..37ad794 100755
--- a/t/t2400-worktree-add.sh
+++ b/t/t2400-worktree-add.sh
@@ -67,11 +67,25 @@
 '
 
 test_expect_success '"add" worktree with lock' '
-	git rev-parse HEAD >expect &&
 	git worktree add --detach --lock here-with-lock main &&
+	test_when_finished "git worktree unlock here-with-lock || :" &&
 	test -f .git/worktrees/here-with-lock/locked
 '
 
+test_expect_success '"add" worktree with lock and reason' '
+	lock_reason="why not" &&
+	git worktree add --detach --lock --reason "$lock_reason" here-with-lock-reason main &&
+	test_when_finished "git worktree unlock here-with-lock-reason || :" &&
+	test -f .git/worktrees/here-with-lock-reason/locked &&
+	echo "$lock_reason" >expect &&
+	test_cmp expect .git/worktrees/here-with-lock-reason/locked
+'
+
+test_expect_success '"add" worktree with reason but no lock' '
+	test_must_fail git worktree add --detach --reason "why not" here-with-reason-only main &&
+	test_path_is_missing .git/worktrees/here-with-reason-only/locked
+'
+
 test_expect_success '"add" worktree from a subdir' '
 	(
 		mkdir sub &&
diff --git a/t/t3202-show-branch-octopus.sh b/t/t3202-show-branch-octopus.sh
deleted file mode 100755
index 5cb0126..0000000
--- a/t/t3202-show-branch-octopus.sh
+++ /dev/null
@@ -1,70 +0,0 @@
-#!/bin/sh
-
-test_description='test show-branch with more than 8 heads'
-
-GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
-export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
-
-. ./test-lib.sh
-
-numbers="1 2 3 4 5 6 7 8 9 10"
-
-test_expect_success 'setup' '
-
-	> file &&
-	git add file &&
-	test_tick &&
-	git commit -m initial &&
-
-	for i in $numbers
-	do
-		git checkout -b branch$i main &&
-		> file$i &&
-		git add file$i &&
-		test_tick &&
-		git commit -m branch$i || return 1
-	done
-
-'
-
-cat > expect << EOF
-! [branch1] branch1
- ! [branch2] branch2
-  ! [branch3] branch3
-   ! [branch4] branch4
-    ! [branch5] branch5
-     ! [branch6] branch6
-      ! [branch7] branch7
-       ! [branch8] branch8
-        ! [branch9] branch9
-         * [branch10] branch10
-----------
-         * [branch10] branch10
-        +  [branch9] branch9
-       +   [branch8] branch8
-      +    [branch7] branch7
-     +     [branch6] branch6
-    +      [branch5] branch5
-   +       [branch4] branch4
-  +        [branch3] branch3
- +         [branch2] branch2
-+          [branch1] branch1
-+++++++++* [branch10^] initial
-EOF
-
-test_expect_success 'show-branch with more than 8 branches' '
-
-	git show-branch $(for i in $numbers; do echo branch$i; done) > out &&
-	test_cmp expect out
-
-'
-
-test_expect_success 'show-branch with showbranch.default' '
-	for i in $numbers; do
-		git config --add showbranch.default branch$i
-	done &&
-	git show-branch >out &&
-	test_cmp expect out
-'
-
-test_done
diff --git a/t/t3202-show-branch.sh b/t/t3202-show-branch.sh
new file mode 100755
index 0000000..ad9902a
--- /dev/null
+++ b/t/t3202-show-branch.sh
@@ -0,0 +1,149 @@
+#!/bin/sh
+
+test_description='test show-branch'
+
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	test_commit initial &&
+	for i in $(test_seq 1 10)
+	do
+		git checkout -b branch$i initial &&
+		test_commit --no-tag branch$i
+	done &&
+	git for-each-ref \
+		--sort=version:refname \
+		--format="%(refname:strip=2)" \
+		"refs/heads/branch*" >branches.sorted &&
+	sed "s/^> //" >expect <<-\EOF
+	> ! [branch1] branch1
+	>  ! [branch2] branch2
+	>   ! [branch3] branch3
+	>    ! [branch4] branch4
+	>     ! [branch5] branch5
+	>      ! [branch6] branch6
+	>       ! [branch7] branch7
+	>        ! [branch8] branch8
+	>         ! [branch9] branch9
+	>          * [branch10] branch10
+	> ----------
+	>          * [branch10] branch10
+	>         +  [branch9] branch9
+	>        +   [branch8] branch8
+	>       +    [branch7] branch7
+	>      +     [branch6] branch6
+	>     +      [branch5] branch5
+	>    +       [branch4] branch4
+	>   +        [branch3] branch3
+	>  +         [branch2] branch2
+	> +          [branch1] branch1
+	> +++++++++* [branch10^] initial
+	EOF
+'
+
+test_expect_success 'show-branch with more than 8 branches' '
+	git show-branch $(cat branches.sorted) >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'show-branch with showbranch.default' '
+	for branch in $(cat branches.sorted)
+	do
+		test_config showbranch.default $branch --add
+	done &&
+	git show-branch >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'show-branch --color output' '
+	sed "s/^> //" >expect <<-\EOF &&
+	> <RED>!<RESET> [branch1] branch1
+	>  <GREEN>!<RESET> [branch2] branch2
+	>   <YELLOW>!<RESET> [branch3] branch3
+	>    <BLUE>!<RESET> [branch4] branch4
+	>     <MAGENTA>!<RESET> [branch5] branch5
+	>      <CYAN>!<RESET> [branch6] branch6
+	>       <BOLD;RED>!<RESET> [branch7] branch7
+	>        <BOLD;GREEN>!<RESET> [branch8] branch8
+	>         <BOLD;YELLOW>!<RESET> [branch9] branch9
+	>          <BOLD;BLUE>*<RESET> [branch10] branch10
+	> ----------
+	>          <BOLD;BLUE>*<RESET> [branch10] branch10
+	>         <BOLD;YELLOW>+<RESET>  [branch9] branch9
+	>        <BOLD;GREEN>+<RESET>   [branch8] branch8
+	>       <BOLD;RED>+<RESET>    [branch7] branch7
+	>      <CYAN>+<RESET>     [branch6] branch6
+	>     <MAGENTA>+<RESET>      [branch5] branch5
+	>    <BLUE>+<RESET>       [branch4] branch4
+	>   <YELLOW>+<RESET>        [branch3] branch3
+	>  <GREEN>+<RESET>         [branch2] branch2
+	> <RED>+<RESET>          [branch1] branch1
+	> <RED>+<RESET><GREEN>+<RESET><YELLOW>+<RESET><BLUE>+<RESET><MAGENTA>+<RESET><CYAN>+<RESET><BOLD;RED>+<RESET><BOLD;GREEN>+<RESET><BOLD;YELLOW>+<RESET><BOLD;BLUE>*<RESET> [branch10^] initial
+	EOF
+	git show-branch --color=always $(cat branches.sorted) >actual.raw &&
+	test_decode_color <actual.raw >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'show branch --remotes' '
+	cat >expect.err <<-\EOF &&
+	No revs to be shown.
+	EOF
+	git show-branch -r 2>actual.err >actual.out &&
+	test_cmp expect.err actual.err &&
+	test_must_be_empty actual.out
+'
+
+test_expect_success 'setup show branch --list' '
+	sed "s/^> //" >expect <<-\EOF
+	>   [branch1] branch1
+	>   [branch2] branch2
+	>   [branch3] branch3
+	>   [branch4] branch4
+	>   [branch5] branch5
+	>   [branch6] branch6
+	>   [branch7] branch7
+	>   [branch8] branch8
+	>   [branch9] branch9
+	> * [branch10] branch10
+	EOF
+'
+
+test_expect_success 'show branch --list' '
+	git show-branch --list $(cat branches.sorted) >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'show branch --list has no --color output' '
+	git show-branch --color=always --list $(cat branches.sorted) >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'show branch --merge-base with one argument' '
+	for branch in $(cat branches.sorted)
+	do
+		git rev-parse $branch >expect &&
+		git show-branch --merge-base $branch >actual &&
+		test_cmp expect actual
+	done
+'
+
+test_expect_success 'show branch --merge-base with two arguments' '
+	for branch in $(cat branches.sorted)
+	do
+		git rev-parse initial >expect &&
+		git show-branch --merge-base initial $branch >actual &&
+		test_cmp expect actual
+	done
+'
+
+test_expect_success 'show branch --merge-base with N arguments' '
+	git rev-parse initial >expect &&
+	git show-branch --merge-base $(cat branches.sorted) >actual &&
+	test_cmp expect actual &&
+
+	git merge-base $(cat branches.sorted) >actual &&
+	test_cmp expect actual
+'
+
+test_done
diff --git a/t/t3800-mktag.sh b/t/t3800-mktag.sh
index 6275c98..0544d58 100755
--- a/t/t3800-mktag.sh
+++ b/t/t3800-mktag.sh
@@ -12,15 +12,93 @@
 # given in the expect.pat file.
 
 check_verify_failure () {
-	test_expect_success "$1" "
-		test_must_fail git mktag <tag.sig 2>message &&
-		grep '$2' message &&
-		if test '$3' != '--no-strict'
+	subject=$1 &&
+	message=$2 &&
+	shift 2 &&
+
+	no_strict= &&
+	fsck_obj_ok= &&
+	no_strict= &&
+	while test $# != 0
+	do
+		case "$1" in
+		--no-strict)
+			no_strict=yes
+			;;
+		--fsck-obj-ok)
+			fsck_obj_ok=yes
+			;;
+		esac &&
+		shift
+	done &&
+
+	test_expect_success "fail with [--[no-]strict]: $subject" '
+		test_must_fail git mktag <tag.sig 2>err &&
+		if test -z "$no_strict"
 		then
-			test_must_fail git mktag --no-strict <tag.sig 2>message.no-strict &&
-			grep '$2' message.no-strict
+			test_must_fail git mktag <tag.sig 2>err2 &&
+			test_cmp err err2
+		else
+			git mktag --no-strict <tag.sig
 		fi
-	"
+	'
+
+	test_expect_success "setup: $subject" '
+		tag_ref=refs/tags/bad_tag &&
+
+		# Reset any leftover state from the last $subject
+		rm -rf bad-tag &&
+
+		git init --bare bad-tag &&
+		bad_tag=$(git -C bad-tag hash-object -t tag -w --stdin --literally <tag.sig)
+	'
+
+	test_expect_success "hash-object & fsck unreachable: $subject" '
+		if test -n "$fsck_obj_ok"
+		then
+			git -C bad-tag fsck
+		else
+			test_must_fail git -C bad-tag fsck
+		fi
+	'
+
+	test_expect_success "update-ref & fsck reachable: $subject" '
+		# Make sure the earlier test created it for us
+		git rev-parse "$bad_tag" &&
+
+		# The update-ref of the bad content will fail, do it
+		# anyway to see if it segfaults
+		test_might_fail git -C bad-tag update-ref "$tag_ref" "$bad_tag" &&
+
+		# Manually create the broken, we cannot do it with
+		# update-ref
+		echo "$bad_tag" >"bad-tag/$tag_ref" &&
+
+		# Unlike fsck-ing unreachable content above, this
+		# will always fail.
+		test_must_fail git -C bad-tag fsck
+	'
+
+	test_expect_success "for-each-ref: $subject" '
+		# Make sure the earlier test created it for us
+		git rev-parse "$bad_tag" &&
+
+		echo "$bad_tag" >"bad-tag/$tag_ref" &&
+
+		printf "%s tag\t%s\n" "$bad_tag" "$tag_ref" >expected &&
+		git -C bad-tag for-each-ref "$tag_ref" >actual &&
+		test_cmp expected actual &&
+
+		test_must_fail git -C bad-tag for-each-ref --format="%(*objectname)"
+	'
+
+	test_expect_success "fast-export & fast-import: $subject" '
+		# Make sure the earlier test created it for us
+		git rev-parse "$bad_tag" &&
+
+		test_must_fail git -C bad-tag fast-export --all &&
+		test_must_fail git -C bad-tag fast-export "$bad_tag"
+	'
 }
 
 test_expect_mktag_success() {
@@ -167,7 +245,8 @@
 EOF
 
 check_verify_failure 'verify object (hash/type) check -- correct type, nonexisting object' \
-	'^fatal: could not read tagged object'
+	'^fatal: could not read tagged object' \
+	--fsck-obj-ok
 
 cat >tag.sig <<EOF
 object $head
@@ -200,7 +279,8 @@
 EOF
 
 check_verify_failure 'verify object (hash/type) check -- mismatched type, valid object' \
-	'^fatal: object.*tagged as.*tree.*but is.*commit'
+	'^fatal: object.*tagged as.*tree.*but is.*commit' \
+	--fsck-obj-ok
 
 ############################################################
 #  9.5. verify object (hash/type) check -- replacement
@@ -229,7 +309,8 @@
 EOF
 
 check_verify_failure 'verify object (hash/type) check -- mismatched type, valid object' \
-	'^fatal: object.*tagged as.*tree.*but is.*blob'
+	'^fatal: object.*tagged as.*tree.*but is.*blob' \
+	--fsck-obj-ok
 
 ############################################################
 # 10. verify tag-name check
@@ -243,7 +324,9 @@
 EOF
 
 check_verify_failure 'verify tag-name check' \
-	'^error:.* badTagName:' '--no-strict'
+	'^error:.* badTagName:' \
+	--no-strict \
+	--fsck-obj-ok
 
 ############################################################
 # 11. tagger line label check #1
@@ -257,7 +340,9 @@
 EOF
 
 check_verify_failure '"tagger" line label check #1' \
-	'^error:.* missingTaggerEntry:' '--no-strict'
+	'^error:.* missingTaggerEntry:' \
+	--no-strict \
+	--fsck-obj-ok
 
 ############################################################
 # 12. tagger line label check #2
@@ -272,7 +357,9 @@
 EOF
 
 check_verify_failure '"tagger" line label check #2' \
-	'^error:.* missingTaggerEntry:' '--no-strict'
+	'^error:.* missingTaggerEntry:' \
+	--no-strict \
+	--fsck-obj-ok
 
 ############################################################
 # 13. allow missing tag author name like fsck
@@ -301,7 +388,9 @@
 EOF
 
 check_verify_failure 'disallow malformed tagger' \
-	'^error:.* badEmail:' '--no-strict'
+	'^error:.* badEmail:' \
+	--no-strict \
+	--fsck-obj-ok
 
 ############################################################
 # 15. allow empty tag email
@@ -425,7 +514,9 @@
 EOF
 
 check_verify_failure 'detect invalid header entry' \
-	'^error:.* extraHeaderEntry:' '--no-strict'
+	'^error:.* extraHeaderEntry:' \
+	--no-strict \
+	--fsck-obj-ok
 
 test_expect_success 'invalid header entry config & fsck' '
 	test_must_fail git mktag <tag.sig &&
diff --git a/t/t4202-log.sh b/t/t4202-log.sh
index 39e746f..9dfead9 100755
--- a/t/t4202-log.sh
+++ b/t/t4202-log.sh
@@ -1915,6 +1915,20 @@
 	test_must_fail git log --exclude-promisor-objects source-a
 '
 
+test_expect_success 'log --decorate includes all levels of tag annotated tags' '
+	git checkout -b branch &&
+	git commit --allow-empty -m "new commit" &&
+	git tag lightweight HEAD &&
+	git tag -m annotated annotated HEAD &&
+	git tag -m double-0 double-0 HEAD &&
+	git tag -m double-1 double-1 double-0 &&
+	cat >expect <<-\EOF &&
+	HEAD -> branch, tag: lightweight, tag: double-1, tag: double-0, tag: annotated
+	EOF
+	git log -1 --format="%D" >actual &&
+	test_cmp expect actual
+'
+
 test_expect_success 'log --end-of-options' '
        git update-ref refs/heads/--source HEAD &&
        git log --end-of-options --source >actual &&
diff --git a/t/t5319-multi-pack-index.sh b/t/t5319-multi-pack-index.sh
index 5641d15..7609f1e 100755
--- a/t/t5319-multi-pack-index.sh
+++ b/t/t5319-multi-pack-index.sh
@@ -410,6 +410,19 @@
 		"git -c core.multipackindex=true fsck"
 '
 
+test_expect_success 'corrupt MIDX is not reused' '
+	corrupt_midx_and_verify $MIDX_BYTE_OFFSET "\377" $objdir \
+		"incorrect object offset" &&
+	git multi-pack-index write 2>err &&
+	test_i18ngrep checksum.mismatch err &&
+	git multi-pack-index verify
+'
+
+test_expect_success 'verify incorrect checksum' '
+	pos=$(($(wc -c <$objdir/pack/multi-pack-index) - 1)) &&
+	corrupt_midx_and_verify $pos "\377" $objdir "incorrect checksum"
+'
+
 test_expect_success 'repack progress off for redirected stderr' '
 	GIT_PROGRESS_DELAY=0 git multi-pack-index --object-dir=$objdir repack 2>err &&
 	test_line_count = 0 err
diff --git a/t/t5411/once-0010-report-status-v1.sh b/t/t5411/once-0010-report-status-v1.sh
index 1233a46..297b109 100644
--- a/t/t5411/once-0010-report-status-v1.sh
+++ b/t/t5411/once-0010-report-status-v1.sh
@@ -28,10 +28,10 @@
 		if test -z "$GIT_DEFAULT_HASH" || test "$GIT_DEFAULT_HASH" = "sha1"
 		then
 			printf "%s %s refs/heads/main\0report-status\n" \
-				$A $B | packetize
+				$A $B | packetize_raw
 		else
 			printf "%s %s refs/heads/main\0report-status object-format=$GIT_DEFAULT_HASH\n" \
-				$A $B | packetize
+				$A $B | packetize_raw
 		fi &&
 		printf "%s %s refs/for/main/topic1\n" \
 			$ZERO_OID $A | packetize &&
diff --git a/t/t5562-http-backend-content-length.sh b/t/t5562-http-backend-content-length.sh
index e5d3d15..05a5806 100755
--- a/t/t5562-http-backend-content-length.sh
+++ b/t/t5562-http-backend-content-length.sh
@@ -63,7 +63,7 @@
 	hash_next=$(git commit-tree -p HEAD -m next HEAD^{tree}) &&
 	{
 		printf "%s %s refs/heads/newbranch\\0report-status object-format=%s\\n" \
-			"$ZERO_OID" "$hash_next" "$(test_oid algo)" | packetize &&
+			"$ZERO_OID" "$hash_next" "$(test_oid algo)" | packetize_raw
 		printf 0000 &&
 		echo "$hash_next" | git pack-objects --stdout
 	} >push_body &&
diff --git a/t/t5570-git-daemon.sh b/t/t5570-git-daemon.sh
index 82c31ab..b87ca06 100755
--- a/t/t5570-git-daemon.sh
+++ b/t/t5570-git-daemon.sh
@@ -194,7 +194,7 @@
 
 test_expect_success FAKENC 'hostname interpolation works after LF-stripping' '
 	{
-		printf "git-upload-pack /interp.git\n\0host=localhost" | packetize
+		printf "git-upload-pack /interp.git\n\0host=localhost" | packetize_raw
 		printf "0000"
 	} >input &&
 	fake_nc "$GIT_DAEMON_HOST_PORT" <input >output &&
diff --git a/t/t5702-protocol-v2.sh b/t/t5702-protocol-v2.sh
index 66af411..78de1ff 100755
--- a/t/t5702-protocol-v2.sh
+++ b/t/t5702-protocol-v2.sh
@@ -599,6 +599,22 @@
 	test_commit -C client three
 }
 
+test_expect_success 'usage: --negotiate-only without --negotiation-tip' '
+	SERVER="server" &&
+	URI="file://$(pwd)/server" &&
+
+	setup_negotiate_only "$SERVER" "$URI" &&
+
+	cat >err.expect <<-\EOF &&
+	fatal: --negotiate-only needs one or more --negotiate-tip=*
+	EOF
+
+	test_must_fail git -c protocol.version=2 -C client fetch \
+		--negotiate-only \
+		origin 2>err.actual &&
+	test_cmp err.expect err.actual
+'
+
 test_expect_success 'file:// --negotiate-only' '
 	SERVER="server" &&
 	URI="file://$(pwd)/server" &&
diff --git a/t/t6006-rev-list-format.sh b/t/t6006-rev-list-format.sh
index 35a2f62..41d0ca0 100755
--- a/t/t6006-rev-list-format.sh
+++ b/t/t6006-rev-list-format.sh
@@ -41,22 +41,59 @@
 	echo "$added_iso88591" | git commit -F - &&
 	head1=$(git rev-parse --verify HEAD) &&
 	head1_short=$(git rev-parse --verify --short $head1) &&
+	head1_short4=$(git rev-parse --verify --short=4 $head1) &&
 	tree1=$(git rev-parse --verify HEAD:) &&
 	tree1_short=$(git rev-parse --verify --short $tree1) &&
 	echo "$changed" > foo &&
 	echo "$changed_iso88591" | git commit -a -F - &&
 	head2=$(git rev-parse --verify HEAD) &&
 	head2_short=$(git rev-parse --verify --short $head2) &&
+	head2_short4=$(git rev-parse --verify --short=4 $head2) &&
 	tree2=$(git rev-parse --verify HEAD:) &&
 	tree2_short=$(git rev-parse --verify --short $tree2) &&
 	git config --unset i18n.commitEncoding
 '
 
-# usage: test_format name format_string [failure] <expected_output
+# usage: test_format [argument...] name format_string [failure] <expected_output
 test_format () {
+	local args=
+	while true
+	do
+		case "$1" in
+		--*)
+			args="$args $1"
+			shift;;
+		*)
+			break;;
+		esac
+	done
 	cat >expect.$1
 	test_expect_${3:-success} "format $1" "
-		git rev-list --pretty=format:'$2' main >output.$1 &&
+		git rev-list $args --pretty=format:'$2' main >output.$1 &&
+		test_cmp expect.$1 output.$1
+	"
+}
+
+# usage: test_pretty [argument...] name format_name [failure] <expected_output
+test_pretty () {
+	local args=
+	while true
+	do
+		case "$1" in
+		--*)
+			args="$args $1"
+			shift;;
+		*)
+			break;;
+		esac
+	done
+	cat >expect.$1
+	test_expect_${3:-success} "pretty $1 (without --no-commit-header)" "
+		git rev-list $args --pretty='$2' main >output.$1 &&
+		test_cmp expect.$1 output.$1
+	"
+	test_expect_${3:-success} "pretty $1 (with --no-commit-header)" "
+		git rev-list $args --no-commit-header --pretty='$2' main >output.$1 &&
 		test_cmp expect.$1 output.$1
 	"
 }
@@ -93,6 +130,20 @@
 $head1_short
 EOF
 
+test_format --no-commit-header hash-no-header %H%n%h <<EOF
+$head2
+$head2_short
+$head1
+$head1_short
+EOF
+
+test_format --abbrev-commit --abbrev=0 --no-commit-header hash-no-header-abbrev %H%n%h <<EOF
+$head2
+$head2_short4
+$head1
+$head1_short4
+EOF
+
 test_format tree %T%n%t <<EOF
 commit $head2
 $tree2
@@ -181,6 +232,31 @@
 
 EOF
 
+test_format --no-commit-header raw-body-no-header %B <<EOF
+$changed
+
+$added
+
+EOF
+
+test_pretty oneline oneline <<EOF
+$head2 $changed
+$head1 $added
+EOF
+
+test_pretty short short <<EOF
+commit $head2
+Author: $GIT_AUTHOR_NAME <$GIT_AUTHOR_EMAIL>
+
+    $changed
+
+commit $head1
+Author: $GIT_AUTHOR_NAME <$GIT_AUTHOR_EMAIL>
+
+    $added
+
+EOF
+
 test_expect_success 'basic colors' '
 	cat >expect <<-EOF &&
 	commit $head2
diff --git a/t/t6400-merge-df.sh b/t/t6400-merge-df.sh
index 38700d2..57a67cf 100755
--- a/t/t6400-merge-df.sh
+++ b/t/t6400-merge-df.sh
@@ -82,13 +82,13 @@
 	git checkout delete^0 &&
 	test_must_fail git merge modify &&
 
-	test 5 -eq $(git ls-files -s | wc -l) &&
-	test 4 -eq $(git ls-files -u | wc -l) &&
+	test_stdout_line_count = 5 git ls-files -s &&
+	test_stdout_line_count = 4 git ls-files -u &&
 	if test "$GIT_TEST_MERGE_ALGORITHM" = ort
 	then
-		test 0 -eq $(git ls-files -o | wc -l)
+		test_stdout_line_count = 0 git ls-files -o
 	else
-		test 1 -eq $(git ls-files -o | wc -l)
+		test_stdout_line_count = 1 git ls-files -o
 	fi &&
 
 	test_path_is_file letters/file &&
@@ -103,13 +103,13 @@
 
 	test_must_fail git merge delete &&
 
-	test 5 -eq $(git ls-files -s | wc -l) &&
-	test 4 -eq $(git ls-files -u | wc -l) &&
+	test_stdout_line_count = 5 git ls-files -s &&
+	test_stdout_line_count = 4 git ls-files -u &&
 	if test "$GIT_TEST_MERGE_ALGORITHM" = ort
 	then
-		test 0 -eq $(git ls-files -o | wc -l)
+		test_stdout_line_count = 0 git ls-files -o
 	else
-		test 1 -eq $(git ls-files -o | wc -l)
+		test_stdout_line_count = 1 git ls-files -o
 	fi &&
 
 	test_path_is_file letters/file &&
diff --git a/t/t6402-merge-rename.sh b/t/t6402-merge-rename.sh
index 425dad9..3da2896 100755
--- a/t/t6402-merge-rename.sh
+++ b/t/t6402-merge-rename.sh
@@ -105,10 +105,8 @@
 	git show-branch &&
 	test_expect_code 1 git pull . white &&
 	git ls-files -s &&
-	git ls-files -u B >b.stages &&
-	test_line_count = 3 b.stages &&
-	git ls-files -s N >n.stages &&
-	test_line_count = 1 n.stages &&
+	test_stdout_line_count = 3 git ls-files -u B &&
+	test_stdout_line_count = 1 git ls-files -s N &&
 	sed -ne "/^g/{
 	p
 	q
@@ -122,10 +120,8 @@
 	git reset --hard &&
 	git checkout red &&
 	test_expect_code 1 git pull . white &&
-	git ls-files -u B >b.stages &&
-	test_line_count = 3 b.stages &&
-	git ls-files -s N >n.stages &&
-	test_line_count = 1 n.stages &&
+	test_stdout_line_count = 3 git ls-files -u B &&
+	test_stdout_line_count = 1 git ls-files -s N &&
 	sed -ne "/^g/{
 	p
 	q
@@ -138,10 +134,8 @@
 	git reset --hard &&
 	git show-branch &&
 	test_expect_code 1 git pull . main &&
-	git ls-files -u B >b.stages &&
-	test_line_count = 3 b.stages &&
-	git ls-files -s N >n.stages &&
-	test_line_count = 1 n.stages &&
+	test_stdout_line_count = 3 git ls-files -u B &&
+	test_stdout_line_count = 1 git ls-files -s N &&
 	sed -ne "/^g/{
 	p
 	q
@@ -154,14 +148,10 @@
 	git reset --hard &&
 	git show-branch &&
 	test_expect_code 1 git pull . blue &&
-	git ls-files -u A >a.stages &&
-	test_line_count = 1 a.stages &&
-	git ls-files -u B >b.stages &&
-	test_line_count = 1 b.stages &&
-	git ls-files -u C >c.stages &&
-	test_line_count = 1 c.stages &&
-	git ls-files -s N >n.stages &&
-	test_line_count = 1 n.stages &&
+	test_stdout_line_count = 1 git ls-files -u A &&
+	test_stdout_line_count = 1 git ls-files -u B &&
+	test_stdout_line_count = 1 git ls-files -u C &&
+	test_stdout_line_count = 1 git ls-files -s N &&
 	sed -ne "/^g/{
 	p
 	q
@@ -330,8 +320,8 @@
 		test_i18ngrep "Adding as dir~HEAD instead" output
 	fi &&
 
-	test 3 -eq "$(git ls-files -u | wc -l)" &&
-	test 2 -eq "$(git ls-files -u dir/file-in-the-way | wc -l)" &&
+	test_stdout_line_count = 3 git ls-files -u &&
+	test_stdout_line_count = 2 git ls-files -u dir/file-in-the-way &&
 
 	test_must_fail git diff --quiet &&
 	test_must_fail git diff --cached --quiet &&
@@ -357,8 +347,8 @@
 		test_i18ngrep "Adding as dir~renamed-file-has-no-conflicts instead" output
 	fi &&
 
-	test 3 -eq "$(git ls-files -u | wc -l)" &&
-	test 2 -eq "$(git ls-files -u dir/file-in-the-way | wc -l)" &&
+	test_stdout_line_count = 3 git ls-files -u &&
+	test_stdout_line_count = 2 git ls-files -u dir/file-in-the-way &&
 
 	test_must_fail git diff --quiet &&
 	test_must_fail git diff --cached --quiet &&
@@ -374,8 +364,8 @@
 	git checkout -q renamed-file-has-conflicts^0 &&
 	test_must_fail git merge --strategy=recursive dir-not-in-way &&
 
-	test 3 -eq "$(git ls-files -u | wc -l)" &&
-	test 3 -eq "$(git ls-files -u dir | wc -l)" &&
+	test_stdout_line_count = 3 git ls-files -u &&
+	test_stdout_line_count = 3 git ls-files -u dir &&
 
 	test_must_fail git diff --quiet &&
 	test_must_fail git diff --cached --quiet &&
@@ -409,14 +399,16 @@
 	git checkout -q renamed-file-has-conflicts^0 &&
 	test_must_fail git merge --strategy=recursive dir-in-way &&
 
-	test 5 -eq "$(git ls-files -u | wc -l)" &&
+	test_stdout_line_count = 5 git ls-files -u &&
 	if test "$GIT_TEST_MERGE_ALGORITHM" = ort
 	then
-		test 3 -eq "$(git ls-files -u dir~HEAD | wc -l)"
+		test_stdout_line_count = 3 git ls-files -u dir~HEAD
 	else
-		test 3 -eq "$(git ls-files -u dir | grep -v file-in-the-way | wc -l)"
+		git ls-files -u dir >out &&
+		test 3 -eq $(grep -v file-in-the-way out | wc -l) &&
+		rm -f out
 	fi &&
-	test 2 -eq "$(git ls-files -u dir/file-in-the-way | wc -l)" &&
+	test_stdout_line_count = 2 git ls-files -u dir/file-in-the-way &&
 
 	test_must_fail git diff --quiet &&
 	test_must_fail git diff --cached --quiet &&
@@ -432,14 +424,16 @@
 	git checkout -q dir-in-way^0 &&
 	test_must_fail git merge --strategy=recursive renamed-file-has-conflicts &&
 
-	test 5 -eq "$(git ls-files -u | wc -l)" &&
+	test_stdout_line_count = 5 git ls-files -u &&
 	if test "$GIT_TEST_MERGE_ALGORITHM" = ort
 	then
-		test 3 -eq "$(git ls-files -u dir~renamed-file-has-conflicts | wc -l)"
+		test_stdout_line_count = 3 git ls-files -u dir~renamed-file-has-conflicts
 	else
-		test 3 -eq "$(git ls-files -u dir | grep -v file-in-the-way | wc -l)"
+		git ls-files -u dir >out &&
+		test 3 -eq $(grep -v file-in-the-way out | wc -l) &&
+		rm -f out
 	fi &&
-	test 2 -eq "$(git ls-files -u dir/file-in-the-way | wc -l)" &&
+	test_stdout_line_count = 2 git ls-files -u dir/file-in-the-way &&
 
 	test_must_fail git diff --quiet &&
 	test_must_fail git diff --cached --quiet &&
@@ -496,9 +490,9 @@
 
 	if test "$GIT_TEST_MERGE_ALGORITHM" = ort
 	then
-		test 2 -eq "$(git ls-files -u | wc -l)"
+		test_stdout_line_count = 2 git ls-files -u
 	else
-		test 1 -eq "$(git ls-files -u | wc -l)"
+		test_stdout_line_count = 1 git ls-files -u
 	fi &&
 
 	test_must_fail git diff --quiet &&
@@ -540,9 +534,9 @@
 		mkdir one &&
 		test_must_fail git merge --strategy=recursive rename-two &&
 
-		test 4 -eq "$(git ls-files -u | wc -l)" &&
-		test 2 -eq "$(git ls-files -u one | wc -l)" &&
-		test 2 -eq "$(git ls-files -u two | wc -l)" &&
+		test_stdout_line_count = 4 git ls-files -u &&
+		test_stdout_line_count = 2 git ls-files -u one &&
+		test_stdout_line_count = 2 git ls-files -u two &&
 
 		test_must_fail git diff --quiet &&
 
@@ -559,9 +553,9 @@
 		mkdir one &&
 		test_must_fail git merge --strategy=recursive rename-two &&
 
-		test 2 -eq "$(git ls-files -u | wc -l)" &&
-		test 1 -eq "$(git ls-files -u one | wc -l)" &&
-		test 1 -eq "$(git ls-files -u two | wc -l)" &&
+		test_stdout_line_count = 2 git ls-files -u &&
+		test_stdout_line_count = 1 git ls-files -u one &&
+		test_stdout_line_count = 1 git ls-files -u two &&
 
 		test_must_fail git diff --quiet &&
 
@@ -582,13 +576,13 @@
 
 	if test "$GIT_TEST_MERGE_ALGORITHM" = ort
 	then
-		test 4 -eq "$(git ls-files -u | wc -l)" &&
-		test 2 -eq "$(git ls-files -u one | wc -l)" &&
-		test 2 -eq "$(git ls-files -u two | wc -l)"
+		test_stdout_line_count = 4 git ls-files -u &&
+		test_stdout_line_count = 2 git ls-files -u one &&
+		test_stdout_line_count = 2 git ls-files -u two
 	else
-		test 2 -eq "$(git ls-files -u | wc -l)" &&
-		test 1 -eq "$(git ls-files -u one | wc -l)" &&
-		test 1 -eq "$(git ls-files -u two | wc -l)"
+		test_stdout_line_count = 2 git ls-files -u &&
+		test_stdout_line_count = 1 git ls-files -u one &&
+		test_stdout_line_count = 1 git ls-files -u two
 	fi &&
 
 	test_must_fail git diff --quiet &&
@@ -631,19 +625,19 @@
 
 	if test "$GIT_TEST_MERGE_ALGORITHM" = ort
 	then
-		test 5 -eq "$(git ls-files -s | wc -l)" &&
-		test 3 -eq "$(git ls-files -u | wc -l)" &&
-		test 1 -eq "$(git ls-files -u one~HEAD | wc -l)" &&
-		test 1 -eq "$(git ls-files -u two~second-rename | wc -l)" &&
-		test 1 -eq "$(git ls-files -u original | wc -l)" &&
-		test 0 -eq "$(git ls-files -o | wc -l)"
+		test_stdout_line_count = 5 git ls-files -s &&
+		test_stdout_line_count = 3 git ls-files -u &&
+		test_stdout_line_count = 1 git ls-files -u one~HEAD &&
+		test_stdout_line_count = 1 git ls-files -u two~second-rename &&
+		test_stdout_line_count = 1 git ls-files -u original &&
+		test_stdout_line_count = 0 git ls-files -o
 	else
-		test 5 -eq "$(git ls-files -s | wc -l)" &&
-		test 3 -eq "$(git ls-files -u | wc -l)" &&
-		test 1 -eq "$(git ls-files -u one | wc -l)" &&
-		test 1 -eq "$(git ls-files -u two | wc -l)" &&
-		test 1 -eq "$(git ls-files -u original | wc -l)" &&
-		test 2 -eq "$(git ls-files -o | wc -l)"
+		test_stdout_line_count = 5 git ls-files -s &&
+		test_stdout_line_count = 3 git ls-files -u &&
+		test_stdout_line_count = 1 git ls-files -u one &&
+		test_stdout_line_count = 1 git ls-files -u two &&
+		test_stdout_line_count = 1 git ls-files -u original &&
+		test_stdout_line_count = 2 git ls-files -o
 	fi &&
 
 	test_path_is_file one/file &&
@@ -679,11 +673,11 @@
 	git checkout -q first-rename-redo^0 &&
 	test_must_fail git merge --strategy=recursive second-rename-redo &&
 
-	test 3 -eq "$(git ls-files -u | wc -l)" &&
-	test 1 -eq "$(git ls-files -u one | wc -l)" &&
-	test 1 -eq "$(git ls-files -u two | wc -l)" &&
-	test 1 -eq "$(git ls-files -u original | wc -l)" &&
-	test 0 -eq "$(git ls-files -o | wc -l)" &&
+	test_stdout_line_count = 3 git ls-files -u &&
+	test_stdout_line_count = 1 git ls-files -u one &&
+	test_stdout_line_count = 1 git ls-files -u two &&
+	test_stdout_line_count = 1 git ls-files -u original &&
+	test_stdout_line_count = 0 git ls-files -o &&
 
 	test_path_is_file one &&
 	test_path_is_file two &&
@@ -861,9 +855,11 @@
 test_expect_success 'merge rename + small change' '
 	git merge rename_branch &&
 
-	test 1 -eq $(git ls-files -s | wc -l) &&
-	test 0 -eq $(git ls-files -o | wc -l) &&
-	test $(git rev-parse HEAD:renamed_file) = $(git rev-parse HEAD~1:file)
+	test_stdout_line_count = 1 git ls-files -s &&
+	test_stdout_line_count = 0 git ls-files -o &&
+	newhash=$(git rev-parse HEAD:renamed_file) &&
+	oldhash=$(git rev-parse HEAD~1:file) &&
+	test $newhash = $oldhash
 '
 
 test_expect_success 'setup for use of extended merge markers' '
diff --git a/t/t6421-merge-partial-clone.sh b/t/t6421-merge-partial-clone.sh
new file mode 100755
index 0000000..36bcd7c3
--- /dev/null
+++ b/t/t6421-merge-partial-clone.sh
@@ -0,0 +1,440 @@
+#!/bin/sh
+
+test_description="limiting blob downloads when merging with partial clones"
+# Uses a methodology similar to
+#   t6042: corner cases with renames but not criss-cross merges
+#   t6036: corner cases with both renames and criss-cross merges
+#   t6423: directory rename detection
+#
+# The setup for all of them, pictorially, is:
+#
+#      A
+#      o
+#     / \
+#  O o   ?
+#     \ /
+#      o
+#      B
+#
+# To help make it easier to follow the flow of tests, they have been
+# divided into sections and each test will start with a quick explanation
+# of what commits O, A, and B contain.
+#
+# Notation:
+#    z/{b,c}   means  files z/b and z/c both exist
+#    x/d_1     means  file x/d exists with content d1.  (Purpose of the
+#                     underscore notation is to differentiate different
+#                     files that might be renamed into each other's paths.)
+
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-merge.sh
+
+test_setup_repo () {
+	test -d server && return
+	test_create_repo server &&
+	(
+		cd server &&
+
+		git config uploadpack.allowfilter 1 &&
+		git config uploadpack.allowanysha1inwant 1 &&
+
+		mkdir -p general &&
+		test_seq 2 9 >general/leap1 &&
+		cp general/leap1 general/leap2 &&
+		echo leap2 >>general/leap2 &&
+
+		mkdir -p basename &&
+		cp general/leap1 basename/numbers &&
+		cp general/leap1 basename/sequence &&
+		cp general/leap1 basename/values &&
+		echo numbers >>basename/numbers &&
+		echo sequence >>basename/sequence &&
+		echo values >>basename/values &&
+
+		mkdir -p dir/unchanged &&
+		mkdir -p dir/subdir/tweaked &&
+		echo a >dir/subdir/a &&
+		echo b >dir/subdir/b &&
+		echo c >dir/subdir/c &&
+		echo d >dir/subdir/d &&
+		echo e >dir/subdir/e &&
+		cp general/leap1 dir/subdir/Makefile &&
+		echo toplevel makefile >>dir/subdir/Makefile &&
+		echo f >dir/subdir/tweaked/f &&
+		echo g >dir/subdir/tweaked/g &&
+		echo h >dir/subdir/tweaked/h &&
+		echo subdirectory makefile >dir/subdir/tweaked/Makefile &&
+		for i in $(test_seq 1 88)
+		do
+			echo content $i >dir/unchanged/file_$i
+		done &&
+		git add . &&
+		git commit -m "O" &&
+
+		git branch O &&
+		git branch A &&
+		git branch B-single &&
+		git branch B-dir &&
+		git branch B-many &&
+
+		git switch A &&
+
+		git rm general/leap* &&
+		mkdir general/ &&
+		test_seq 1 9 >general/jump1 &&
+		cp general/jump1 general/jump2 &&
+		echo leap2 >>general/jump2 &&
+
+		rm basename/numbers basename/sequence basename/values &&
+		mkdir -p basename/subdir/
+		cp general/jump1 basename/subdir/numbers &&
+		cp general/jump1 basename/subdir/sequence &&
+		cp general/jump1 basename/subdir/values &&
+		echo numbers >>basename/subdir/numbers &&
+		echo sequence >>basename/subdir/sequence &&
+		echo values >>basename/subdir/values &&
+
+		git rm dir/subdir/tweaked/f &&
+		echo more >>dir/subdir/e &&
+		echo more >>dir/subdir/Makefile &&
+		echo more >>dir/subdir/tweaked/Makefile &&
+		mkdir dir/subdir/newsubdir &&
+		echo rust code >dir/subdir/newsubdir/newfile.rs &&
+		git mv dir/subdir/e dir/subdir/newsubdir/ &&
+		git mv dir folder &&
+		git add . &&
+		git commit -m "A" &&
+
+		git switch B-single &&
+		echo new first line >dir/subdir/Makefile &&
+		cat general/leap1 >>dir/subdir/Makefile &&
+		echo toplevel makefile >>dir/subdir/Makefile &&
+		echo perl code >general/newfile.pl &&
+		git add . &&
+		git commit -m "B-single" &&
+
+		git switch B-dir &&
+		echo java code >dir/subdir/newfile.java &&
+		echo scala code >dir/subdir/newfile.scala &&
+		echo groovy code >dir/subdir/newfile.groovy &&
+		git add . &&
+		git commit -m "B-dir" &&
+
+		git switch B-many &&
+		test_seq 2 10 >general/leap1 &&
+		rm general/leap2 &&
+		cp general/leap1 general/leap2 &&
+		echo leap2 >>general/leap2 &&
+
+		rm basename/numbers basename/sequence basename/values &&
+		mkdir -p basename/subdir/
+		cp general/leap1 basename/subdir/numbers &&
+		cp general/leap1 basename/subdir/sequence &&
+		cp general/leap1 basename/subdir/values &&
+		echo numbers >>basename/subdir/numbers &&
+		echo sequence >>basename/subdir/sequence &&
+		echo values >>basename/subdir/values &&
+
+		mkdir dir/subdir/newsubdir/ &&
+		echo c code >dir/subdir/newfile.c &&
+		echo python code >dir/subdir/newsubdir/newfile.py &&
+		git add . &&
+		git commit -m "B-many" &&
+
+		git switch A
+	)
+}
+
+# Testcase: Objects downloaded for single relevant rename
+#   Commit O:
+#              general/{leap1_O, leap2_O}
+#              basename/{numbers_O, sequence_O, values_O}
+#              dir/subdir/{a,b,c,d,e_O,Makefile_TOP_O}
+#              dir/subdir/tweaked/{f,g,h,Makefile_SUB_O}
+#              dir/unchanged/<LOTS OF FILES>
+#   Commit A:
+#     (Rename leap->jump, rename basename/ -> basename/subdir/, rename dir/
+#      -> folder/, move e into newsubdir, add newfile.rs, remove f, modify
+#      both both Makefiles and jumps)
+#              general/{jump1_A, jump2_A}
+#              basename/subdir/{numbers_A, sequence_A, values_A}
+#              folder/subdir/{a,b,c,d,Makefile_TOP_A}
+#              folder/subdir/newsubdir/{e_A,newfile.rs}
+#              folder/subdir/tweaked/{g,h,Makefile_SUB_A}
+#              folder/unchanged/<LOTS OF FILES>
+#   Commit B(-single):
+#     (add newfile.pl, tweak Makefile_TOP)
+#              general/{leap1_O, leap2_O,newfile.pl}
+#              basename/{numbers_O, sequence_O, values_O}
+#              dir/{a,b,c,d,e_O,Makefile_TOP_B}
+#              dir/tweaked/{f,g,h,Makefile_SUB_O}
+#              dir/unchanged/<LOTS OF FILES>
+#   Expected:
+#              general/{jump1_A, jump2_A,newfile.pl}
+#              basename/subdir/{numbers_A, sequence_A, values_A}
+#              folder/subdir/{a,b,c,d,Makefile_TOP_Merged}
+#              folder/subdir/newsubdir/{e_A,newfile.rs}
+#              folder/subdir/tweaked/{g,h,Makefile_SUB_A}
+#              folder/unchanged/<LOTS OF FILES>
+#
+# Objects that need to be fetched:
+#   Rename detection:
+#     Side1 (O->A):
+#       Basename-matches rename detection only needs to fetch these objects:
+#         Makefile_TOP_O, Makefile_TOP_A
+#         (Despite many renames, all others are content irrelevant.  They
+#          are also location irrelevant because newfile.rs was added on
+#          the side doing the directory rename, and newfile.pl was added to
+#          a directory that was not renamed on either side.)
+#       General rename detection only needs to fetch these objects:
+#         <None>
+#          (Even though newfile.rs, jump[12], basename/subdir/*, and e
+#          could all be used as destinations in rename detection, the
+#          basename detection for Makefile matches up all relevant
+#          sources, so these other files never end up needing to be
+#          used)
+#     Side2 (O->B):
+#       Basename-matches rename detection only needs to fetch these objects:
+#         <None>
+#         (there are no deleted files, so no possible sources)
+#       General rename detection only needs to fetch these objects:
+#         <None>
+#         (there are no deleted files, so no possible sources)
+#   Merge:
+#     3-way content merge needs to grab these objects:
+#       Makefile_TOP_B
+#   Nothing else needs to fetch objects
+#
+#   Summary: 2 fetches (1 for 2 objects, 1 for 1 object)
+#
+test_expect_merge_algorithm failure success 'Objects downloaded for single relevant rename' '
+	test_setup_repo &&
+	git clone --sparse --filter=blob:none "file://$(pwd)/server" objects-single &&
+	(
+		cd objects-single &&
+
+		git rev-list --objects --all --missing=print |
+			grep "^?" | sort >missing-objects-before &&
+
+		git checkout -q origin/A &&
+
+		GIT_TRACE2_PERF="$(pwd)/trace.output" git \
+			-c merge.directoryRenames=true merge --no-stat \
+			--no-progress origin/B-single &&
+
+		# Check the number of objects we reported we would fetch
+		cat >expect <<-EOF &&
+		fetch_count:2
+		fetch_count:1
+		EOF
+		grep fetch_count trace.output | cut -d "|" -f 9 | tr -d " ." >actual &&
+		test_cmp expect actual &&
+
+		# Check the number of fetch commands exec-ed
+		grep d0.*fetch.negotiationAlgorithm trace.output >fetches &&
+		test_line_count = 2 fetches &&
+
+		git rev-list --objects --all --missing=print |
+			grep "^?" | sort >missing-objects-after &&
+		comm -2 -3 missing-objects-before missing-objects-after >old &&
+		comm -1 -3 missing-objects-before missing-objects-after >new &&
+		# No new missing objects
+		test_must_be_empty new &&
+		# Fetched 2 + 1 = 3 objects
+		test_line_count = 3 old
+	)
+'
+
+# Testcase: Objects downloaded for directory rename
+#   Commit O:
+#              general/{leap1_O, leap2_O}
+#              basename/{numbers_O, sequence_O, values_O}
+#              dir/subdir/{a,b,c,d,e_O,Makefile_TOP_O}
+#              dir/subdir/tweaked/{f,g,h,Makefile_SUB_O}
+#              dir/unchanged/<LOTS OF FILES>
+#   Commit A:
+#     (Rename leap->jump, rename basename/ -> basename/subdir/, rename dir/ ->
+#      folder/, move e into newsubdir, add newfile.rs, remove f, modify
+#      both Makefiles and jumps)
+#              general/{jump1_A, jump2_A}
+#              basename/subdir/{numbers_A, sequence_A, values_A}
+#              folder/subdir/{a,b,c,d,Makefile_TOP_A}
+#              folder/subdir/newsubdir/{e_A,newfile.rs}
+#              folder/subdir/tweaked/{g,h,Makefile_SUB_A}
+#              folder/unchanged/<LOTS OF FILES>
+#   Commit B(-dir):
+#     (add dir/subdir/newfile.{java,scala,groovy}
+#              general/{leap1_O, leap2_O}
+#              basename/{numbers_O, sequence_O, values_O}
+#              dir/subdir/{a,b,c,d,e_O,Makefile_TOP_O,
+#                          newfile.java,newfile.scala,newfile.groovy}
+#              dir/subdir/tweaked/{f,g,h,Makefile_SUB_O}
+#              dir/unchanged/<LOTS OF FILES>
+#   Expected:
+#              general/{jump1_A, jump2_A}
+#              basename/subdir/{numbers_A, sequence_A, values_A}
+#              folder/subdir/{a,b,c,d,Makefile_TOP_A,
+#                             newfile.java,newfile.scala,newfile.groovy}
+#              folder/subdir/newsubdir/{e_A,newfile.rs}
+#              folder/subdir/tweaked/{g,h,Makefile_SUB_A}
+#              folder/unchanged/<LOTS OF FILES>
+#
+# Objects that need to be fetched:
+#   Makefile_TOP_O, Makefile_TOP_A
+#   Makefile_SUB_O, Makefile_SUB_A
+#   e_O, e_A
+#   * Despite A's rename of jump->leap, those renames are irrelevant.
+#   * Despite A's rename of basename/ -> basename/subdir/, those renames are
+#     irrelevant.
+#   * Because of A's rename of dir/ -> folder/ and B-dir's addition of
+#     newfile.* into dir/subdir/, we need to determine directory renames.
+#     (Technically, there are enough exact renames to determine directory
+#      rename detection, but the current implementation always does
+#      basename searching before directory rename detection.  Running it
+#      also before basename searching would mean doing directory rename
+#      detection twice, but it's a bit expensive to do that and cases like
+#      this are not all that common.)
+#   Summary: 1 fetches for 6 objects
+#
+test_expect_merge_algorithm failure success 'Objects downloaded when a directory rename triggered' '
+	test_setup_repo &&
+	git clone --sparse --filter=blob:none "file://$(pwd)/server" objects-dir &&
+	(
+		cd objects-dir &&
+
+		git rev-list --objects --all --missing=print |
+			grep "^?" | sort >missing-objects-before &&
+
+		git checkout -q origin/A &&
+
+		GIT_TRACE2_PERF="$(pwd)/trace.output" git \
+			-c merge.directoryRenames=true merge --no-stat \
+			--no-progress origin/B-dir &&
+
+		# Check the number of objects we reported we would fetch
+		cat >expect <<-EOF &&
+		fetch_count:6
+		EOF
+		grep fetch_count trace.output | cut -d "|" -f 9 | tr -d " ." >actual &&
+		test_cmp expect actual &&
+
+		# Check the number of fetch commands exec-ed
+		grep d0.*fetch.negotiationAlgorithm trace.output >fetches &&
+		test_line_count = 1 fetches &&
+
+		git rev-list --objects --all --missing=print |
+			grep "^?" | sort >missing-objects-after &&
+		comm -2 -3 missing-objects-before missing-objects-after >old &&
+		comm -1 -3 missing-objects-before missing-objects-after >new &&
+		# No new missing objects
+		test_must_be_empty new &&
+		# Fetched 6 objects
+		test_line_count = 6 old
+	)
+'
+
+# Testcase: Objects downloaded with lots of renames and modifications
+#   Commit O:
+#              general/{leap1_O, leap2_O}
+#              basename/{numbers_O, sequence_O, values_O}
+#              dir/subdir/{a,b,c,d,e_O,Makefile_TOP_O}
+#              dir/subdir/tweaked/{f,g,h,Makefile_SUB_O}
+#              dir/unchanged/<LOTS OF FILES>
+#   Commit A:
+#     (Rename leap->jump, rename basename/ -> basename/subdir/, rename dir/
+#      -> folder/, move e into newsubdir, add newfile.rs, remove f, modify
+#      both both Makefiles and jumps)
+#              general/{jump1_A, jump2_A}
+#              basename/subdir/{numbers_A, sequence_A, values_A}
+#              folder/subdir/{a,b,c,d,Makefile_TOP_A}
+#              folder/subdir/newsubdir/{e_A,newfile.rs}
+#              folder/subdir/tweaked/{g,h,Makefile_SUB_A}
+#              folder/unchanged/<LOTS OF FILES>
+#   Commit B(-minimal):
+#     (modify both leaps, rename basename/ -> basename/subdir/, add
+#      newfile.{c,py})
+#              general/{leap1_B, leap2_B}
+#              basename/subdir/{numbers_B, sequence_B, values_B}
+#              dir/{a,b,c,d,e_O,Makefile_TOP_O,newfile.c}
+#              dir/tweaked/{f,g,h,Makefile_SUB_O,newfile.py}
+#              dir/unchanged/<LOTS OF FILES>
+#   Expected:
+#              general/{jump1_Merged, jump2_Merged}
+#              basename/subdir/{numbers_Merged, sequence_Merged, values_Merged}
+#              folder/subdir/{a,b,c,d,Makefile_TOP_A,newfile.c}
+#              folder/subdir/newsubdir/e_A
+#              folder/subdir/tweaked/{g,h,Makefile_SUB_A,newfile.py}
+#              folder/unchanged/<LOTS OF FILES>
+#
+# Objects that need to be fetched:
+#   Rename detection:
+#     Side1 (O->A):
+#       Basename-matches rename detection only needs to fetch these objects:
+#         numbers_O, numbers_A
+#         sequence_O, sequence_A
+#         values_O, values_A
+#         Makefile_TOP_O, Makefile_TOP_A
+#         Makefile_SUB_O, Makefile_SUB_A
+#         e_O, e_A
+#       General rename detection only needs to fetch these objects:
+#         leap1_O, leap2_O
+#         jump1_A, jump2_A, newfile.rs
+#         (only need remaining relevant sources, but any relevant sources need
+#          to be matched against all possible unpaired destinations)
+#     Side2 (O->B):
+#       Basename-matches rename detection only needs to fetch these objects:
+#         numbers_B
+#         sequence_B
+#         values_B
+#       (because numbers_O, sequence_O, and values_O already fetched above)
+#       General rename detection only needs to fetch these objects:
+#         <None>
+#   Merge:
+#     3-way content merge needs to grab these objects:
+#       leap1_B
+#       leap2_B
+#   Nothing else needs to fetch objects
+#
+#   Summary: 4 fetches (1 for 6 objects, 1 for 8, 1 for 3, 1 for 2)
+#
+test_expect_merge_algorithm failure success 'Objects downloaded with lots of renames and modifications' '
+	test_setup_repo &&
+	git clone --sparse --filter=blob:none "file://$(pwd)/server" objects-many &&
+	(
+		cd objects-many &&
+
+		git rev-list --objects --all --missing=print |
+			grep "^?" | sort >missing-objects-before &&
+
+		git checkout -q origin/A &&
+
+		GIT_TRACE2_PERF="$(pwd)/trace.output" git \
+			-c merge.directoryRenames=true merge --no-stat \
+			--no-progress origin/B-many &&
+
+		# Check the number of objects we reported we would fetch
+		cat >expect <<-EOF &&
+		fetch_count:12
+		fetch_count:5
+		fetch_count:3
+		fetch_count:2
+		EOF
+		grep fetch_count trace.output | cut -d "|" -f 9 | tr -d " ." >actual &&
+		test_cmp expect actual &&
+
+		# Check the number of fetch commands exec-ed
+		grep d0.*fetch.negotiationAlgorithm trace.output >fetches &&
+		test_line_count = 4 fetches &&
+
+		git rev-list --objects --all --missing=print |
+			grep "^?" | sort >missing-objects-after &&
+		comm -2 -3 missing-objects-before missing-objects-after >old &&
+		comm -1 -3 missing-objects-before missing-objects-after >new &&
+		# No new missing objects
+		test_must_be_empty new &&
+		# Fetched 12 + 5 + 3 + 2 = 22 objects
+		test_line_count = 22 old
+	)
+'
+
+test_done
diff --git a/t/t6423-merge-rename-directories.sh b/t/t6423-merge-rename-directories.sh
index be84d22..4af4fb0 100755
--- a/t/t6423-merge-rename-directories.sh
+++ b/t/t6423-merge-rename-directories.sh
@@ -454,7 +454,7 @@
 #   the directory renamed, but the files within it. (see 1b)
 #
 #   If renames split a directory into two or more others, the directory
-#   with the most renames, "wins" (see 1c).  However, see the testcases
+#   with the most renames, "wins" (see 1f).  However, see the testcases
 #   in section 2, plus testcases 3a and 4a.
 ###########################################################################
 
@@ -5024,6 +5024,181 @@
 	)
 '
 
+# Testcase 12i, Directory rename causes rename-to-self
+#   Commit O: source/{subdir/foo, bar, baz_1}
+#   Commit A: source/{foo, bar, baz_1}
+#   Commit B: source/{subdir/{foo, bar}, baz_2}
+#   Expected: source/{foo, bar, baz_2}, with conflicts on
+#                source/bar vs. source/subdir/bar
+
+test_setup_12i () {
+	test_create_repo 12i &&
+	(
+		cd 12i &&
+
+		mkdir -p source/subdir &&
+		echo foo >source/subdir/foo &&
+		echo bar >source/bar &&
+		echo baz >source/baz &&
+		git add source &&
+		git commit -m orig &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git switch A &&
+		git mv source/subdir/foo source/foo &&
+		git commit -m A &&
+
+		git switch B &&
+		git mv source/bar source/subdir/bar &&
+		echo more baz >>source/baz &&
+		git commit -m B
+	)
+}
+
+test_expect_success '12i: Directory rename causes rename-to-self' '
+	test_setup_12i &&
+	(
+		cd 12i &&
+
+		git checkout A^0 &&
+
+		test_must_fail git -c merge.directoryRenames=conflict merge -s recursive B^0 &&
+
+		test_path_is_missing source/subdir &&
+		test_path_is_file source/bar &&
+		test_path_is_file source/baz &&
+
+		git ls-files | uniq >tracked &&
+		test_line_count = 3 tracked &&
+
+		git status --porcelain -uno >actual &&
+		cat >expect <<-\EOF &&
+		UU source/bar
+		 M source/baz
+		EOF
+		test_cmp expect actual
+	)
+'
+
+# Testcase 12j, Directory rename to root causes rename-to-self
+#   Commit O: {subdir/foo, bar, baz_1}
+#   Commit A: {foo, bar, baz_1}
+#   Commit B: {subdir/{foo, bar}, baz_2}
+#   Expected: {foo, bar, baz_2}, with conflicts on bar vs. subdir/bar
+
+test_setup_12j () {
+	test_create_repo 12j &&
+	(
+		cd 12j &&
+
+		mkdir -p subdir &&
+		echo foo >subdir/foo &&
+		echo bar >bar &&
+		echo baz >baz &&
+		git add . &&
+		git commit -m orig &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git switch A &&
+		git mv subdir/foo foo &&
+		git commit -m A &&
+
+		git switch B &&
+		git mv bar subdir/bar &&
+		echo more baz >>baz &&
+		git commit -m B
+	)
+}
+
+test_expect_success '12j: Directory rename to root causes rename-to-self' '
+	test_setup_12j &&
+	(
+		cd 12j &&
+
+		git checkout A^0 &&
+
+		test_must_fail git -c merge.directoryRenames=conflict merge -s recursive B^0 &&
+
+		test_path_is_missing subdir &&
+		test_path_is_file bar &&
+		test_path_is_file baz &&
+
+		git ls-files | uniq >tracked &&
+		test_line_count = 3 tracked &&
+
+		git status --porcelain -uno >actual &&
+		cat >expect <<-\EOF &&
+		UU bar
+		 M baz
+		EOF
+		test_cmp expect actual
+	)
+'
+
+# Testcase 12k, Directory rename with sibling causes rename-to-self
+#   Commit O: dirB/foo, dirA/{bar, baz_1}
+#   Commit A: dirA/{foo, bar, baz_1}
+#   Commit B: dirB/{foo, bar}, dirA/baz_2
+#   Expected: dirA/{foo, bar, baz_2}, with conflicts on dirA/bar vs. dirB/bar
+
+test_setup_12k () {
+	test_create_repo 12k &&
+	(
+		cd 12k &&
+
+		mkdir dirA dirB &&
+		echo foo >dirB/foo &&
+		echo bar >dirA/bar &&
+		echo baz >dirA/baz &&
+		git add . &&
+		git commit -m orig &&
+
+		git branch O &&
+		git branch A &&
+		git branch B &&
+
+		git switch A &&
+		git mv dirB/* dirA/ &&
+		git commit -m A &&
+
+		git switch B &&
+		git mv dirA/bar dirB/bar &&
+		echo more baz >>dirA/baz &&
+		git commit -m B
+	)
+}
+
+test_expect_success '12k: Directory rename with sibling causes rename-to-self' '
+	test_setup_12k &&
+	(
+		cd 12k &&
+
+		git checkout A^0 &&
+
+		test_must_fail git -c merge.directoryRenames=conflict merge -s recursive B^0 &&
+
+		test_path_is_missing dirB &&
+		test_path_is_file dirA/bar &&
+		test_path_is_file dirA/baz &&
+
+		git ls-files | uniq >tracked &&
+		test_line_count = 3 tracked &&
+
+		git status --porcelain -uno >actual &&
+		cat >expect <<-\EOF &&
+		UU dirA/bar
+		 M dirA/baz
+		EOF
+		test_cmp expect actual
+	)
+'
+
 ###########################################################################
 # SECTION 13: Checking informational and conflict messages
 #
diff --git a/t/t7500-commit-template-squash-signoff.sh b/t/t7500-commit-template-squash-signoff.sh
index 7d02f79..54c2082 100755
--- a/t/t7500-commit-template-squash-signoff.sh
+++ b/t/t7500-commit-template-squash-signoff.sh
@@ -498,7 +498,7 @@
 cat >expected-template <<EOF
 
 # Please enter the commit message for your changes. Lines starting
-# with '#' will be ignored, and an empty message aborts the commit.
+# with '#' will be ignored.
 #
 # Author:    A U Thor <author@example.com>
 #
diff --git a/t/t7509-commit-authorship.sh b/t/t7509-commit-authorship.sh
index ee6c474..d568593 100755
--- a/t/t7509-commit-authorship.sh
+++ b/t/t7509-commit-authorship.sh
@@ -147,7 +147,7 @@
 	test_tick &&
 	git commit -am "cherry-pick 1" --author="Cherry <cherry@pick.er>" &&
 	git tag cherry-pick-head &&
-	git rev-parse cherry-pick-head >.git/CHERRY_PICK_HEAD &&
+	git update-ref CHERRY_PICK_HEAD $(git rev-parse cherry-pick-head) &&
 	echo "This is a MERGE_MSG" >.git/MERGE_MSG &&
 	echo "cherry-pick 1b" >>foo &&
 	test_tick &&
@@ -162,7 +162,7 @@
 '
 
 test_expect_success '--reset-author with CHERRY_PICK_HEAD' '
-	git rev-parse cherry-pick-head >.git/CHERRY_PICK_HEAD &&
+	git update-ref CHERRY_PICK_HEAD $(git rev-parse cherry-pick-head) &&
 	echo "cherry-pick 2" >>foo &&
 	test_tick &&
 	git commit -am "cherry-pick 2" --reset-author &&
diff --git a/t/t7519-status-fsmonitor.sh b/t/t7519-status-fsmonitor.sh
index 637391c..deea88d 100755
--- a/t/t7519-status-fsmonitor.sh
+++ b/t/t7519-status-fsmonitor.sh
@@ -73,6 +73,7 @@
 	expect*
 	actual*
 	marker*
+	trace2*
 	EOF
 '
 
@@ -383,4 +384,52 @@
 	)
 '
 
+# Usage:
+# check_sparse_index_behavior [!]
+# If "!" is supplied, then we verify that we do not call ensure_full_index
+# during a call to 'git status'. Otherwise, we verify that we _do_ call it.
+check_sparse_index_behavior () {
+	git status --porcelain=v2 >expect &&
+	git sparse-checkout init --cone --sparse-index &&
+	git sparse-checkout set dir1 dir2 &&
+	GIT_TRACE2_EVENT="$(pwd)/trace2.txt" GIT_TRACE2_EVENT_NESTING=10 \
+		git status --porcelain=v2 >actual &&
+	test_region $1 index ensure_full_index trace2.txt &&
+	test_region fsm_hook query trace2.txt &&
+	test_cmp expect actual &&
+	rm trace2.txt &&
+	git sparse-checkout disable
+}
+
+test_expect_success 'status succeeds with sparse index' '
+	git reset --hard &&
+
+	test_config core.fsmonitor "$TEST_DIRECTORY/t7519/fsmonitor-all" &&
+	check_sparse_index_behavior ! &&
+
+	write_script .git/hooks/fsmonitor-test<<-\EOF &&
+		printf "last_update_token\0"
+	EOF
+	git config core.fsmonitor .git/hooks/fsmonitor-test &&
+	check_sparse_index_behavior ! &&
+
+	write_script .git/hooks/fsmonitor-test<<-\EOF &&
+		printf "last_update_token\0"
+		printf "dir1/modified\0"
+	EOF
+	check_sparse_index_behavior ! &&
+
+	cp -r dir1 dir1a &&
+	git add dir1a &&
+	git commit -m "add dir1a" &&
+
+	# This one modifies outside the sparse-checkout definition
+	# and hence we expect to expand the sparse-index.
+	write_script .git/hooks/fsmonitor-test<<-\EOF &&
+		printf "last_update_token\0"
+		printf "dir1a/modified\0"
+	EOF
+	check_sparse_index_behavior
+'
+
 test_done
diff --git a/t/t9001-send-email.sh b/t/t9001-send-email.sh
index e9dc58f..57fc10e 100755
--- a/t/t9001-send-email.sh
+++ b/t/t9001-send-email.sh
@@ -1368,6 +1368,16 @@
 	! grep "X-Mailer" stdout
 '
 
+test_expect_success $PREREQ 'sendemail.identity: bool variable without a value' '
+	git -c sendemail.xmailer \
+		send-email \
+		--dry-run \
+		--from="nobody@example.com" \
+		$patches >stdout &&
+	grep "To: default@example.com" stdout &&
+	grep "X-Mailer" stdout
+'
+
 test_expect_success $PREREQ '--no-to overrides sendemail.to' '
 	git send-email \
 		--dry-run \
@@ -2092,6 +2102,18 @@
 	do_xmailer_test 1 "--xmailer"
 '
 
+test_expect_success $PREREQ '--[no-]xmailer with sendemail.xmailer' '
+	test_when_finished "test_unconfig sendemail.xmailer" &&
+	cat >>.git/config <<-\EOF &&
+	[sendemail]
+		xmailer
+	EOF
+	test_config sendemail.xmailer true &&
+	do_xmailer_test 1 "" &&
+	do_xmailer_test 0 "--no-xmailer" &&
+	do_xmailer_test 1 "--xmailer"
+'
+
 test_expect_success $PREREQ '--[no-]xmailer with sendemail.xmailer=false' '
 	test_config sendemail.xmailer false &&
 	do_xmailer_test 0 "" &&
@@ -2099,6 +2121,13 @@
 	do_xmailer_test 1 "--xmailer"
 '
 
+test_expect_success $PREREQ '--[no-]xmailer with sendemail.xmailer=' '
+	test_config sendemail.xmailer "" &&
+	do_xmailer_test 0 "" &&
+	do_xmailer_test 0 "--no-xmailer" &&
+	do_xmailer_test 1 "--xmailer"
+'
+
 test_expect_success $PREREQ 'setup expected-list' '
 	git send-email \
 	--dry-run \
diff --git a/t/t9300-fast-import.sh b/t/t9300-fast-import.sh
index 1aea943..aa55b41 100755
--- a/t/t9300-fast-import.sh
+++ b/t/t9300-fast-import.sh
@@ -1538,7 +1538,6 @@
 	commit refs/heads/O1
 	# -- ignore all of this text
 	committer $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> $GIT_COMMITTER_DATE
-	# $GIT_COMMITTER_NAME has inserted here for his benefit.
 	data <<COMMIT
 	dirty directory copy
 	COMMIT
diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
index b281047..e28411b 100644
--- a/t/test-lib-functions.sh
+++ b/t/test-lib-functions.sh
@@ -845,6 +845,32 @@
 	fi
 }
 
+# SYNOPSIS:
+# 	test_stdout_line_count <bin-ops> <value> <cmd> [<args>...]
+#
+# test_stdout_line_count checks that the output of a command has the number
+# of lines it ought to. For example:
+#
+# test_stdout_line_count = 3 git ls-files -u
+# test_stdout_line_count -gt 10 ls
+test_stdout_line_count () {
+	local ops val trashdir &&
+	if test "$#" -le 3
+	then
+		BUG "expect 3 or more arguments"
+	fi &&
+	ops="$1" &&
+	val="$2" &&
+	shift 2 &&
+	if ! trashdir="$(git rev-parse --git-dir)/trash"; then
+		BUG "expect to be run inside a worktree"
+	fi &&
+	mkdir -p "$trashdir" &&
+	"$@" >"$trashdir/output" &&
+	test_line_count "$ops" "$val" "$trashdir/output"
+}
+
+
 test_file_size () {
 	test "$#" -ne 1 && BUG "1 param"
 	test-tool path-utils file-size "$1"
@@ -1453,46 +1479,24 @@
 	)
 } 7>&2 2>&4
 
-# convert function arguments or stdin (if not arguments given) to pktline
-# representation. If multiple arguments are given, they are separated by
-# whitespace and put in a single packet. Note that data containing NULs must be
-# given on stdin, and that empty input becomes an empty packet, not a flush
-# packet (for that you can just print 0000 yourself).
+# These functions are historical wrappers around "test-tool pkt-line"
+# for older tests. Use "test-tool pkt-line" itself in new tests.
 packetize () {
 	if test $# -gt 0
 	then
 		packet="$*"
 		printf '%04x%s' "$((4 + ${#packet}))" "$packet"
 	else
-		perl -e '
-			my $packet = do { local $/; <STDIN> };
-			printf "%04x%s", 4 + length($packet), $packet;
-		'
+		test-tool pkt-line pack
 	fi
 }
 
-# Parse the input as a series of pktlines, writing the result to stdout.
-# Sideband markers are removed automatically, and the output is routed to
-# stderr if appropriate.
-#
-# NUL bytes are converted to "\\0" for ease of parsing with text tools.
+packetize_raw () {
+	test-tool pkt-line pack-raw-stdin
+}
+
 depacketize () {
-	perl -e '
-		while (read(STDIN, $len, 4) == 4) {
-			if ($len eq "0000") {
-				print "FLUSH\n";
-			} else {
-				read(STDIN, $buf, hex($len) - 4);
-				$buf =~ s/\0/\\0/g;
-				if ($buf =~ s/^[\x2\x3]//) {
-					print STDERR $buf;
-				} else {
-					$buf =~ s/^\x1//;
-					print $buf;
-				}
-			}
-		}
-	'
+	test-tool pkt-line unpack
 }
 
 # Converts base-16 data into base-8. The output is given as a sequence of
diff --git a/transport.c b/transport.c
index 50f5830..17e9629 100644
--- a/transport.c
+++ b/transport.c
@@ -147,9 +147,11 @@
 	transport->hash_algo = data->header.hash_algo;
 
 	for (i = 0; i < data->header.references.nr; i++) {
-		struct ref_list_entry *e = data->header.references.list + i;
-		struct ref *ref = alloc_ref(e->name);
-		oidcpy(&ref->old_oid, &e->oid);
+		struct string_list_item *e = data->header.references.items + i;
+		const char *name = e->string;
+		struct ref *ref = alloc_ref(name);
+		struct object_id *oid = e->util;
+		oidcpy(&ref->old_oid, oid);
 		ref->next = result;
 		result = ref;
 	}
@@ -175,6 +177,7 @@
 	struct bundle_transport_data *data = transport->data;
 	if (data->fd > 0)
 		close(data->fd);
+	bundle_header_release(&data->header);
 	free(data);
 	return 0;
 }
@@ -1052,7 +1055,7 @@
 	struct transport *ret = xcalloc(1, sizeof(*ret));
 
 	ret->progress = isatty(2);
-	string_list_init(&ret->pack_lockfiles, 1);
+	string_list_init_dup(&ret->pack_lockfiles);
 
 	if (!remote)
 		BUG("No remote provided to transport_get()");
@@ -1081,6 +1084,7 @@
 		die(_("git-over-rsync is no longer supported"));
 	} else if (url_is_local_not_ssh(url) && is_file(url) && is_bundle(url, 1)) {
 		struct bundle_transport_data *data = xcalloc(1, sizeof(*data));
+		bundle_header_init(&data->header);
 		transport_check_allowed("file");
 		ret->data = data;
 		ret->vtable = &bundle_vtable;
diff --git a/unpack-trees.c b/unpack-trees.c
index f88a69f..0a5135a 100644
--- a/unpack-trees.c
+++ b/unpack-trees.c
@@ -600,6 +600,13 @@
 {
 	ce->ce_flags |= CE_UNPACKED;
 
+	/*
+	 * If this is a sparse directory, don't advance cache_bottom.
+	 * That will be advanced later using the cache-tree data.
+	 */
+	if (S_ISSPARSEDIR(ce->ce_mode))
+		return;
+
 	if (o->cache_bottom < o->src_index->cache_nr &&
 	    o->src_index->cache[o->cache_bottom] == ce) {
 		int bottom = o->cache_bottom;
@@ -797,7 +804,7 @@
 		BUG("We need cache-tree to do this optimization");
 
 	/*
-	 * Do what unpack_callback() and unpack_nondirectories() normally
+	 * Do what unpack_callback() and unpack_single_entry() normally
 	 * do. But we walk all paths in an iterative loop instead.
 	 *
 	 * D/F conflicts and higher stage entries are not a concern
@@ -976,6 +983,7 @@
 	int pathlen, ce_len;
 	const char *ce_name;
 	int cmp;
+	unsigned ce_mode;
 
 	/*
 	 * If we have not precomputed the traverse path, it is quicker
@@ -998,7 +1006,8 @@
 	ce_len -= pathlen;
 	ce_name = ce->name + pathlen;
 
-	return df_name_compare(ce_name, ce_len, S_IFREG, name, namelen, mode);
+	ce_mode = S_ISSPARSEDIR(ce->ce_mode) ? S_IFDIR : S_IFREG;
+	return df_name_compare(ce_name, ce_len, ce_mode, name, namelen, mode);
 }
 
 static int compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
@@ -1008,6 +1017,16 @@
 		return cmp;
 
 	/*
+	 * At this point, we know that we have a prefix match. If ce
+	 * is a sparse directory, then allow an exact match. This only
+	 * works when the input name is a directory, since ce->name
+	 * ends in a directory separator.
+	 */
+	if (S_ISSPARSEDIR(ce->ce_mode) &&
+	    ce->ce_namelen == traverse_path_len(info, tree_entry_len(n)) + 1)
+		return 0;
+
+	/*
 	 * Even if the beginning compared identically, the ce should
 	 * compare as bigger than a directory leading up to it!
 	 */
@@ -1033,13 +1052,15 @@
 	const struct name_entry *n,
 	int stage,
 	struct index_state *istate,
-	int is_transient)
+	int is_transient,
+	int is_sparse_directory)
 {
 	size_t len = traverse_path_len(info, tree_entry_len(n));
+	size_t alloc_len = is_sparse_directory ? len + 1 : len;
 	struct cache_entry *ce =
 		is_transient ?
-		make_empty_transient_cache_entry(len, NULL) :
-		make_empty_cache_entry(istate, len);
+		make_empty_transient_cache_entry(alloc_len, NULL) :
+		make_empty_cache_entry(istate, alloc_len);
 
 	ce->ce_mode = create_ce_mode(n->mode);
 	ce->ce_flags = create_ce_flags(stage);
@@ -1048,6 +1069,13 @@
 	/* len+1 because the cache_entry allocates space for NUL */
 	make_traverse_path(ce->name, len + 1, info, n->path, n->pathlen);
 
+	if (is_sparse_directory) {
+		ce->name[len] = '/';
+		ce->name[len + 1] = '\0';
+		ce->ce_namelen++;
+		ce->ce_flags |= CE_SKIP_WORKTREE;
+	}
+
 	return ce;
 }
 
@@ -1056,21 +1084,28 @@
  * without actually calling it. If you change the logic here you may need to
  * check and change there as well.
  */
-static int unpack_nondirectories(int n, unsigned long mask,
-				 unsigned long dirmask,
-				 struct cache_entry **src,
-				 const struct name_entry *names,
-				 const struct traverse_info *info)
+static int unpack_single_entry(int n, unsigned long mask,
+			       unsigned long dirmask,
+			       struct cache_entry **src,
+			       const struct name_entry *names,
+			       const struct traverse_info *info)
 {
 	int i;
 	struct unpack_trees_options *o = info->data;
 	unsigned long conflicts = info->df_conflicts | dirmask;
 
-	/* Do we have *only* directories? Nothing to do */
 	if (mask == dirmask && !src[0])
 		return 0;
 
 	/*
+	 * When we have a sparse directory entry for src[0],
+	 * then this isn't necessarily a directory-file conflict.
+	 */
+	if (mask == dirmask && src[0] &&
+	    S_ISSPARSEDIR(src[0]->ce_mode))
+		conflicts = 0;
+
+	/*
 	 * Ok, we've filled in up to any potential index entry in src[0],
 	 * now do the rest.
 	 */
@@ -1099,7 +1134,9 @@
 		 * not stored in the index.  otherwise construct the
 		 * cache entry from the index aware logic.
 		 */
-		src[i + o->merge] = create_ce_entry(info, names + i, stage, &o->result, o->merge);
+		src[i + o->merge] = create_ce_entry(info, names + i, stage,
+						    &o->result, o->merge,
+						    bit & dirmask);
 	}
 
 	if (o->merge) {
@@ -1203,16 +1240,71 @@
 	return -1;
 }
 
+/*
+ * Given a sparse directory entry 'ce', compare ce->name to
+ * info->name + '/' + p->path + '/' if info->name is non-empty.
+ * Compare ce->name to p->path + '/' otherwise. Note that
+ * ce->name must end in a trailing '/' because it is a sparse
+ * directory entry.
+ */
+static int sparse_dir_matches_path(const struct cache_entry *ce,
+				   struct traverse_info *info,
+				   const struct name_entry *p)
+{
+	assert(S_ISSPARSEDIR(ce->ce_mode));
+	assert(ce->name[ce->ce_namelen - 1] == '/');
+
+	if (info->namelen)
+		return ce->ce_namelen == info->namelen + p->pathlen + 2 &&
+		       ce->name[info->namelen] == '/' &&
+		       !strncmp(ce->name, info->name, info->namelen) &&
+		       !strncmp(ce->name + info->namelen + 1, p->path, p->pathlen);
+	return ce->ce_namelen == p->pathlen + 1 &&
+	       !strncmp(ce->name, p->path, p->pathlen);
+}
+
 static struct cache_entry *find_cache_entry(struct traverse_info *info,
 					    const struct name_entry *p)
 {
+	struct cache_entry *ce;
 	int pos = find_cache_pos(info, p->path, p->pathlen);
 	struct unpack_trees_options *o = info->data;
 
 	if (0 <= pos)
 		return o->src_index->cache[pos];
-	else
+
+	/*
+	 * Check for a sparse-directory entry named "path/".
+	 * Due to the input p->path not having a trailing
+	 * slash, the negative 'pos' value overshoots the
+	 * expected position, hence "-2" instead of "-1".
+	 */
+	pos = -pos - 2;
+
+	if (pos < 0 || pos >= o->src_index->cache_nr)
 		return NULL;
+
+	/*
+	 * Due to lexicographic sorting and sparse directory
+	 * entries ending with a trailing slash, our path as a
+	 * sparse directory (e.g "subdir/") and	our path as a
+	 * file (e.g. "subdir") might be separated by other
+	 * paths (e.g. "subdir-").
+	 */
+	while (pos >= 0) {
+		ce = o->src_index->cache[pos];
+
+		if (strncmp(ce->name, p->path, p->pathlen))
+			return NULL;
+
+		if (S_ISSPARSEDIR(ce->ce_mode) &&
+		    sparse_dir_matches_path(ce, info, p))
+			return ce;
+
+		pos--;
+	}
+
+	return NULL;
 }
 
 static void debug_path(struct traverse_info *info)
@@ -1248,6 +1340,21 @@
 }
 
 /*
+ * Returns true if and only if the given cache_entry is a
+ * sparse-directory entry that matches the given name_entry
+ * from the tree walk at the given traverse_info.
+ */
+static int is_sparse_directory_entry(struct cache_entry *ce,
+				     struct name_entry *name,
+				     struct traverse_info *info)
+{
+	if (!ce || !name || !S_ISSPARSEDIR(ce->ce_mode))
+		return 0;
+
+	return sparse_dir_matches_path(ce, info, name);
+}
+
+/*
  * Note that traverse_by_cache_tree() duplicates some logic in this function
  * without actually calling it. If you change the logic here you may need to
  * check and change there as well.
@@ -1303,7 +1410,7 @@
 		}
 	}
 
-	if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
+	if (unpack_single_entry(n, mask, dirmask, src, names, info) < 0)
 		return -1;
 
 	if (o->merge && src[0]) {
@@ -1333,9 +1440,12 @@
 			}
 		}
 
-		if (traverse_trees_recursive(n, dirmask, mask & ~dirmask,
-					     names, info) < 0)
+		if (!is_sparse_directory_entry(src[0], names, info) &&
+		    traverse_trees_recursive(n, dirmask, mask & ~dirmask,
+						    names, info) < 0) {
 			return -1;
+		}
+
 		return mask;
 	}
 
diff --git a/worktree.c b/worktree.c
index 237517b..092a4f9 100644
--- a/worktree.c
+++ b/worktree.c
@@ -265,6 +265,7 @@
 }
 
 /* convenient wrapper to deal with NULL strbuf */
+__attribute__((format (printf, 2, 3)))
 static void strbuf_addf_gently(struct strbuf *buf, const char *fmt, ...)
 {
 	va_list params;
diff --git a/wt-status.c b/wt-status.c
index 42b6735..eaed30e 100644
--- a/wt-status.c
+++ b/wt-status.c
@@ -639,7 +639,7 @@
 		 * mode by passing a command line option we do not ignore any
 		 * changed submodule SHA-1s when comparing index and HEAD, no
 		 * matter what is configured. Otherwise the user won't be
-		 * shown any submodules she manually added (and which are
+		 * shown any submodules manually added (and which are
 		 * staged to be committed), which would be really confusing.
 		 */
 		handle_ignore_submodules_arg(&rev.diffopt, "dirty");
@@ -657,6 +657,36 @@
 	clear_pathspec(&rev.prune_data);
 }
 
+static int add_file_to_list(const struct object_id *oid,
+			    struct strbuf *base, const char *path,
+			    unsigned int mode, void *context)
+{
+	struct string_list_item *it;
+	struct wt_status_change_data *d;
+	struct wt_status *s = context;
+	struct strbuf full_name = STRBUF_INIT;
+
+	if (S_ISDIR(mode))
+		return READ_TREE_RECURSIVE;
+
+	strbuf_add(&full_name, base->buf, base->len);
+	strbuf_addstr(&full_name, path);
+	it = string_list_insert(&s->change, full_name.buf);
+	d = it->util;
+	if (!d) {
+		CALLOC_ARRAY(d, 1);
+		it->util = d;
+	}
+
+	d->index_status = DIFF_STATUS_ADDED;
+	/* Leave {mode,oid}_head zero for adds. */
+	d->mode_index = mode;
+	oidcpy(&d->oid_index, oid);
+	s->committable = 1;
+	strbuf_release(&full_name);
+	return 0;
+}
+
 static void wt_status_collect_changes_initial(struct wt_status *s)
 {
 	struct index_state *istate = s->repo->index;
@@ -671,6 +701,27 @@
 			continue;
 		if (ce_intent_to_add(ce))
 			continue;
+		if (S_ISSPARSEDIR(ce->ce_mode)) {
+			/*
+			 * This is a sparse directory entry, so we want to collect all
+			 * of the added files within the tree. This requires recursively
+			 * expanding the trees to find the elements that are new in this
+			 * tree and marking them with DIFF_STATUS_ADDED.
+			 */
+			struct strbuf base = STRBUF_INIT;
+			struct pathspec ps = { 0 };
+			struct tree *tree = lookup_tree(istate->repo, &ce->oid);
+
+			ps.recursive = 1;
+			ps.has_wildcard = 1;
+			ps.max_depth = -1;
+
+			strbuf_add(&base, ce->name, ce->ce_namelen);
+			read_tree_at(istate->repo, tree, &base, &ps,
+				     add_file_to_list, s);
+			continue;
+		}
+
 		it = string_list_insert(&s->change, ce->name);
 		d = it->util;
 		if (!d) {
@@ -699,14 +750,13 @@
 static void wt_status_collect_untracked(struct wt_status *s)
 {
 	int i;
-	struct dir_struct dir;
+	struct dir_struct dir = DIR_INIT;
 	uint64_t t_begin = getnanotime();
 	struct index_state *istate = s->repo->index;
 
 	if (!s->show_untracked_files)
 		return;
 
-	dir_init(&dir);
 	if (s->show_untracked_files != SHOW_ALL_UNTRACKED_FILES)
 		dir.flags |=
 			DIR_SHOW_OTHER_DIRECTORIES | DIR_HIDE_EMPTY_DIRECTORIES;
@@ -1493,9 +1543,12 @@
 	if (s->state.sparse_checkout_percentage == SPARSE_CHECKOUT_DISABLED)
 		return;
 
-	status_printf_ln(s, color,
-			 _("You are in a sparse checkout with %d%% of tracked files present."),
-			 s->state.sparse_checkout_percentage);
+	if (s->state.sparse_checkout_percentage == SPARSE_CHECKOUT_SPARSE_INDEX)
+		status_printf_ln(s, color, _("You are in a sparse checkout."));
+	else
+		status_printf_ln(s, color,
+				_("You are in a sparse checkout with %d%% of tracked files present."),
+				s->state.sparse_checkout_percentage);
 	wt_longstatus_print_trailer(s);
 }
 
@@ -1653,6 +1706,11 @@
 		return;
 	}
 
+	if (r->index->sparse_index) {
+		state->sparse_checkout_percentage = SPARSE_CHECKOUT_SPARSE_INDEX;
+		return;
+	}
+
 	for (i = 0; i < r->index->cache_nr; i++) {
 		struct cache_entry *ce = r->index->cache[i];
 		if (ce_skip_worktree(ce))
diff --git a/wt-status.h b/wt-status.h
index 0d32799b..ab9cc9d 100644
--- a/wt-status.h
+++ b/wt-status.h
@@ -78,6 +78,7 @@
 };
 
 #define SPARSE_CHECKOUT_DISABLED -1
+#define SPARSE_CHECKOUT_SPARSE_INDEX -2
 
 struct wt_status_state {
 	int merge_in_progress;