diff --git a/Documentation/RelNotes/2.28.0.txt b/Documentation/RelNotes/2.28.0.txt
index 9fc6dc3..b54c6a0 100644
--- a/Documentation/RelNotes/2.28.0.txt
+++ b/Documentation/RelNotes/2.28.0.txt
@@ -19,6 +19,16 @@
  * The check in "git fsck" to ensure that the tree objects are sorted
    still had corner cases it missed unsorted entries.
 
+ * The interface to redact sensitive information in the trace output
+   has been simplified.
+
+ * The command line completion (in contrib/) learned to complete
+   options that the "git switch" command takes.
+
+ * "git diff" used to take arguments in random and nonsense range
+   notation, e.g. "git diff A..B C", "git diff A..B C...D", etc.,
+   which has been cleaned up.
+
 
 Performance, Internal Implementation, Development Support etc.
 
@@ -50,6 +60,22 @@
  * Workaround breakage in MSVC build, where "curl-config --cflags"
    gives settings appropriate for GCC build.
 
+ * Code clean-up of "git clean" resulted in a fix of recent
+   performance regression.
+
+ * Code clean-up in the codepath that serves "git fetch" continues.
+
+ * "git merge-base --is-ancestor" is taught to take advantage of the
+   commit graph.
+
+ * Rewrite of parts of the scripted "git submodule" Porcelain command
+   continues; this time it is "git submodule set-branch" subcommand's
+   turn.
+
+ * The "fetch/clone" protocol has been updated to allow the server to
+   instruct the clients to grab pre-packaged packfile(s) in addition
+   to the packed object data coming over the wire.
+
 
 Fixes since v2.27
 -----------------
@@ -99,6 +125,21 @@
  * Use of negative pathspec, while collecting paths including
    untracked ones in the working tree, was broken.
 
+ * The same worktree directory must be registered only once, but
+   "git worktree move" allowed this invariant to be violated, which
+   has been corrected.
+   (merge 810382ed37 es/worktree-duplicate-paths later to maint).
+
+ * The effect of sparse checkout settings on submodules is documented.
+   (merge e7d7c73249 en/sparse-with-submodule-doc later to maint).
+
+ * Code clean-up around "git branch" with a minor bugfix.
+   (merge dc44639904 dl/branch-cleanup later to maint).
+
+ * A branch name used in a test has been clarified to match what is
+   going on.
+   (merge 08dc26061f pb/t4014-unslave later to maint).
+
  * Other code cleanup, docfix, build fix, etc.
    (merge 2c31a7aa44 jx/pkt-line-doc-count-fix later to maint).
    (merge d63ae31962 cb/t5608-cleanup later to maint).
diff --git a/Documentation/git-diff.txt b/Documentation/git-diff.txt
index 37781cf..1018110 100644
--- a/Documentation/git-diff.txt
+++ b/Documentation/git-diff.txt
@@ -11,15 +11,17 @@
 [verse]
 'git diff' [<options>] [<commit>] [--] [<path>...]
 'git diff' [<options>] --cached [<commit>] [--] [<path>...]
-'git diff' [<options>] <commit> <commit> [--] [<path>...]
+'git diff' [<options>] <commit> [<commit>...] <commit> [--] [<path>...]
+'git diff' [<options>] <commit>...<commit> [--] [<path>...]
 'git diff' [<options>] <blob> <blob>
 'git diff' [<options>] --no-index [--] <path> <path>
 
 DESCRIPTION
 -----------
 Show changes between the working tree and the index or a tree, changes
-between the index and a tree, changes between two trees, changes between
-two blob objects, or changes between two files on disk.
+between the index and a tree, changes between two trees, changes resulting
+from a merge, changes between two blob objects, or changes between two
+files on disk.
 
 'git diff' [<options>] [--] [<path>...]::
 
@@ -67,6 +69,15 @@
 	one side is omitted, it will have the same effect as
 	using HEAD instead.
 
+'git diff' [<options>] <commit> [<commit>...] <commit> [--] [<path>...]::
+
+	This form is to view the results of a merge commit.  The first
+	listed <commit> must be the merge itself; the remaining two or
+	more commits should be its parents.  A convenient way to produce
+	the desired set of revisions is to use the {caret}@ suffix.
+	For instance, if `master` names a merge commit, `git diff master
+	master^@` gives the same combined diff as `git show master`.
+
 'git diff' [<options>] <commit>\...<commit> [--] [<path>...]::
 
 	This form is to view the changes on the branch containing
@@ -196,7 +207,8 @@
 linkgit:git-log[1],
 linkgit:gitdiffcore[7],
 linkgit:git-format-patch[1],
-linkgit:git-apply[1]
+linkgit:git-apply[1],
+linkgit:git-show[1]
 
 GIT
 ---
diff --git a/Documentation/git-http-fetch.txt b/Documentation/git-http-fetch.txt
index 666b042..4deb489 100644
--- a/Documentation/git-http-fetch.txt
+++ b/Documentation/git-http-fetch.txt
@@ -9,7 +9,7 @@
 SYNOPSIS
 --------
 [verse]
-'git http-fetch' [-c] [-t] [-a] [-d] [-v] [-w filename] [--recover] [--stdin] <commit> <url>
+'git http-fetch' [-c] [-t] [-a] [-d] [-v] [-w filename] [--recover] [--stdin | --packfile=<hash> | <commit>] <url>
 
 DESCRIPTION
 -----------
@@ -40,6 +40,13 @@
 
 		<commit-id>['\t'<filename-as-in--w>]
 
+--packfile=<hash>::
+	Instead of a commit id on the command line (which is not expected in
+	this case), 'git http-fetch' fetches the packfile directly at the given
+	URL and uses index-pack to generate corresponding .idx and .keep files.
+	The hash is used to determine the name of the temporary file and is
+	arbitrary. The output of index-pack is printed to stdout.
+
 --recover::
 	Verify that everything reachable from target is fetched.  Used after
 	an earlier fetch is interrupted.
diff --git a/Documentation/git-sparse-checkout.txt b/Documentation/git-sparse-checkout.txt
index 7c8943a..a0eeaeb 100644
--- a/Documentation/git-sparse-checkout.txt
+++ b/Documentation/git-sparse-checkout.txt
@@ -200,10 +200,32 @@
 SUBMODULES
 ----------
 
-If your repository contains one or more submodules, then those submodules will
-appear based on which you initialized with the `git submodule` command. If
-your sparse-checkout patterns exclude an initialized submodule, then that
-submodule will still appear in your working directory.
+If your repository contains one or more submodules, then submodules
+are populated based on interactions with the `git submodule` command.
+Specifically, `git submodule init -- <path>` will ensure the submodule
+at `<path>` is present, while `git submodule deinit [-f] -- <path>`
+will remove the files for the submodule at `<path>` (including any
+untracked files, uncommitted changes, and unpushed history).  Similar
+to how sparse-checkout removes files from the working tree but still
+leaves entries in the index, deinitialized submodules are removed from
+the working directory but still have an entry in the index.
+
+Since submodules may have unpushed changes or untracked files,
+removing them could result in data loss.  Thus, changing sparse
+inclusion/exclusion rules will not cause an already checked out
+submodule to be removed from the working copy.  Said another way, just
+as `checkout` will not cause submodules to be automatically removed or
+initialized even when switching between branches that remove or add
+submodules, using `sparse-checkout` to reduce or expand the scope of
+"interesting" files will not cause submodules to be automatically
+deinitialized or initialized either.
+
+Further, the above facts mean that there are multiple reasons that
+"tracked" files might not be present in the working copy: sparsity
+pattern application from sparse-checkout, and submodule initialization
+state.  Thus, commands like `git grep` that work on tracked files in
+the working copy may return results that are limited by either or both
+of these restrictions.
 
 
 SEE ALSO
diff --git a/Documentation/git-worktree.txt b/Documentation/git-worktree.txt
index 85d92c9..4796c3c 100644
--- a/Documentation/git-worktree.txt
+++ b/Documentation/git-worktree.txt
@@ -126,7 +126,9 @@
 	locked working tree path, specify `--force` twice.
 +
 `move` refuses to move a locked working tree unless `--force` is specified
-twice.
+twice. If the destination is already assigned to some other working tree but is
+missing (for instance, if `<new-path>` was deleted manually), then `--force`
+allows the move to proceed; use --force twice if the destination is locked.
 +
 `remove` refuses to remove an unclean working tree unless `--force` is used.
 To remove a locked working tree, specify `--force` twice.
diff --git a/Documentation/git.txt b/Documentation/git.txt
index 40bd32f..3e50065 100644
--- a/Documentation/git.txt
+++ b/Documentation/git.txt
@@ -775,11 +775,10 @@
 	See `GIT_TRACE2` for available trace output options and
 	link:technical/api-trace2.html[Trace2 documentation] for full details.
 
-`GIT_REDACT_COOKIES`::
-	This can be set to a comma-separated list of strings. When a curl trace
-	is enabled (see `GIT_TRACE_CURL` above), whenever a "Cookies:" header
-	sent by the client is dumped, values of cookies whose key is in that
-	list (case-sensitive) are redacted.
+`GIT_TRACE_REDACT`::
+	By default, when tracing is activated, Git redacts the values of
+	cookies, the "Authorization:" header, and the "Proxy-Authorization:"
+	header. Set this variable to `0` to prevent this redaction.
 
 `GIT_LITERAL_PATHSPECS`::
 	Setting this variable to `1` will cause Git to treat all
diff --git a/Documentation/technical/packfile-uri.txt b/Documentation/technical/packfile-uri.txt
new file mode 100644
index 0000000..318713a
--- /dev/null
+++ b/Documentation/technical/packfile-uri.txt
@@ -0,0 +1,78 @@
+Packfile URIs
+=============
+
+This feature allows servers to serve part of their packfile response as URIs.
+This allows server designs that improve scalability in bandwidth and CPU usage
+(for example, by serving some data through a CDN), and (in the future) provides
+some measure of resumability to clients.
+
+This feature is available only in protocol version 2.
+
+Protocol
+--------
+
+The server advertises the `packfile-uris` capability.
+
+If the client then communicates which protocols (HTTPS, etc.) it supports with
+a `packfile-uris` argument, the server MAY send a `packfile-uris` section
+directly before the `packfile` section (right after `wanted-refs` if it is
+sent) containing URIs of any of the given protocols. The URIs point to
+packfiles that use only features that the client has declared that it supports
+(e.g. ofs-delta and thin-pack). See protocol-v2.txt for the documentation of
+this section.
+
+Clients should then download and index all the given URIs (in addition to
+downloading and indexing the packfile given in the `packfile` section of the
+response) before performing the connectivity check.
+
+Server design
+-------------
+
+The server can be trivially made compatible with the proposed protocol by
+having it advertise `packfile-uris`, tolerating the client sending
+`packfile-uris`, and never sending any `packfile-uris` section. But we should
+include some sort of non-trivial implementation in the Minimum Viable Product,
+at least so that we can test the client.
+
+This is the implementation: a feature, marked experimental, that allows the
+server to be configured by one or more `uploadpack.blobPackfileUri=<sha1>
+<uri>` entries. Whenever the list of objects to be sent is assembled, all such
+blobs are excluded, replaced with URIs. The client will download those URIs,
+expecting them to each point to packfiles containing single blobs.
+
+Client design
+-------------
+
+The client has a config variable `fetch.uriprotocols` that determines which
+protocols the end user is willing to use. By default, this is empty.
+
+When the client downloads the given URIs, it should store them with "keep"
+files, just like it does with the packfile in the `packfile` section. These
+additional "keep" files can only be removed after the refs have been updated -
+just like the "keep" file for the packfile in the `packfile` section.
+
+The division of work (initial fetch + additional URIs) introduces convenient
+points for resumption of an interrupted clone - such resumption can be done
+after the Minimum Viable Product (see "Future work").
+
+Future work
+-----------
+
+The protocol design allows some evolution of the server and client without any
+need for protocol changes, so only a small-scoped design is included here to
+form the MVP. For example, the following can be done:
+
+ * On the server, more sophisticated means of excluding objects (e.g. by
+   specifying a commit to represent that commit and all objects that it
+   references).
+ * On the client, resumption of clone. If a clone is interrupted, information
+   could be recorded in the repository's config and a "clone-resume" command
+   can resume the clone in progress. (Resumption of subsequent fetches is more
+   difficult because that must deal with the user wanting to use the repository
+   even after the fetch was interrupted.)
+
+There are some possible features that will require a change in protocol:
+
+ * Additional HTTP headers (e.g. authentication)
+ * Byte range support
+ * Different file formats referenced by URIs (e.g. raw object)
diff --git a/Documentation/technical/protocol-v2.txt b/Documentation/technical/protocol-v2.txt
index 3996d70..5852f49 100644
--- a/Documentation/technical/protocol-v2.txt
+++ b/Documentation/technical/protocol-v2.txt
@@ -325,13 +325,26 @@
 	indicating its sideband (1, 2, or 3), and the server may send "0005\2"
 	(a PKT-LINE of sideband 2 with no payload) as a keepalive packet.
 
+If the 'packfile-uris' feature is advertised, the following argument
+can be included in the client's request as well as the potential
+addition of the 'packfile-uris' section in the server's response as
+explained below.
+
+    packfile-uris <comma-separated list of protocols>
+	Indicates to the server that the client is willing to receive
+	URIs of any of the given protocols in place of objects in the
+	sent packfile. Before performing the connectivity check, the
+	client should download from all given URIs. Currently, the
+	protocols supported are "http" and "https".
+
 The response of `fetch` is broken into a number of sections separated by
 delimiter packets (0001), with each section beginning with its section
-header.
+header. Most sections are sent only when the packfile is sent.
 
-    output = *section
-    section = (acknowledgments | shallow-info | wanted-refs | packfile)
-	      (flush-pkt | delim-pkt)
+    output = acknowledgements flush-pkt |
+	     [acknowledgments delim-pkt] [shallow-info delim-pkt]
+	     [wanted-refs delim-pkt] [packfile-uris delim-pkt]
+	     packfile flush-pkt
 
     acknowledgments = PKT-LINE("acknowledgments" LF)
 		      (nak | *ack)
@@ -349,13 +362,17 @@
 		  *PKT-LINE(wanted-ref LF)
     wanted-ref = obj-id SP refname
 
+    packfile-uris = PKT-LINE("packfile-uris" LF) *packfile-uri
+    packfile-uri = PKT-LINE(40*(HEXDIGIT) SP *%x20-ff LF)
+
     packfile = PKT-LINE("packfile" LF)
 	       *PKT-LINE(%x01-03 *%x00-ff)
 
     acknowledgments section
-	* If the client determines that it is finished with negotiations
-	  by sending a "done" line, the acknowledgments sections MUST be
-	  omitted from the server's response.
+	* If the client determines that it is finished with negotiations by
+	  sending a "done" line (thus requiring the server to send a packfile),
+	  the acknowledgments sections MUST be omitted from the server's
+	  response.
 
 	* Always begins with the section header "acknowledgments"
 
@@ -406,9 +423,6 @@
 	  which the client has not indicated was shallow as a part of
 	  its request.
 
-	* This section is only included if a packfile section is also
-	  included in the response.
-
     wanted-refs section
 	* This section is only included if the client has requested a
 	  ref using a 'want-ref' line and if a packfile section is also
@@ -422,6 +436,20 @@
 	* The server MUST NOT send any refs which were not requested
 	  using 'want-ref' lines.
 
+    packfile-uris section
+	* This section is only included if the client sent
+	  'packfile-uris' and the server has at least one such URI to
+	  send.
+
+	* Always begins with the section header "packfile-uris".
+
+	* For each URI the server sends, it sends a hash of the pack's
+	  contents (as output by git index-pack) followed by the URI.
+
+	* The hashes are 40 hex characters long. When Git upgrades to a new
+	  hash algorithm, this might need to be updated. (It should match
+	  whatever index-pack outputs after "pack\t" or "keep\t".
+
     packfile section
 	* This section is only included if the client has sent 'want'
 	  lines in its request and either requested that no more
diff --git a/bugreport.c b/bugreport.c
index 28f4568..09579e2 100644
--- a/bugreport.c
+++ b/bugreport.c
@@ -180,7 +180,9 @@
 		die(_("couldn't create a new file at '%s'"), report_path.buf);
 	}
 
-	strbuf_write_fd(&buffer, report);
+	if (write_in_full(report, buffer.buf, buffer.len) < 0)
+		die_errno(_("unable to write to %s"), report_path.buf);
+
 	close(report);
 
 	/*
diff --git a/builtin/branch.c b/builtin/branch.c
index accb61b..99633ad 100644
--- a/builtin/branch.c
+++ b/builtin/branch.c
@@ -693,7 +693,7 @@
 		list = 1;
 
 	if (!!delete + !!rename + !!copy + !!new_upstream + !!show_current +
-	    list + unset_upstream > 1)
+	    list + edit_description + unset_upstream > 1)
 		usage_with_options(builtin_branch_usage, options);
 
 	if (filter.abbrev == -1)
diff --git a/builtin/clean.c b/builtin/clean.c
index 4ca12bc..5a9c29a 100644
--- a/builtin/clean.c
+++ b/builtin/clean.c
@@ -924,12 +924,6 @@
 			     0);
 
 	memset(&dir, 0, sizeof(dir));
-	if (ignored_only)
-		dir.flags |= DIR_SHOW_IGNORED;
-
-	if (ignored && ignored_only)
-		die(_("-x and -X cannot be used together"));
-
 	if (!interactive && !dry_run && !force) {
 		if (config_set)
 			die(_("clean.requireForce set to true and neither -i, -n, nor -f given; "
@@ -946,6 +940,13 @@
 
 	dir.flags |= DIR_SHOW_OTHER_DIRECTORIES;
 
+	if (ignored && ignored_only)
+		die(_("-x and -X cannot be used together"));
+	if (!ignored)
+		setup_standard_excludes(&dir);
+	if (ignored_only)
+		dir.flags |= DIR_SHOW_IGNORED;
+
 	if (argc) {
 		/*
 		 * Remaining args implies pathspecs specified, and we should
@@ -954,15 +955,41 @@
 		remove_directories = 1;
 	}
 
-	if (remove_directories)
-		dir.flags |= DIR_SHOW_IGNORED_TOO | DIR_KEEP_UNTRACKED_CONTENTS;
+	if (remove_directories && !ignored_only) {
+		/*
+		 * We need to know about ignored files too:
+		 *
+		 * If (ignored), then we will delete ignored files as well.
+		 *
+		 * If (!ignored), then even though we not are doing
+		 * anything with ignored files, we need to know about them
+		 * so that we can avoid deleting a directory of untracked
+		 * files that also contains an ignored file within it.
+		 *
+		 * For the (!ignored) case, since we only need to avoid
+		 * deleting ignored files, we can set
+		 * DIR_SHOW_IGNORED_TOO_MODE_MATCHING in order to avoid
+		 * recursing into a directory which is itself ignored.
+		 */
+		dir.flags |= DIR_SHOW_IGNORED_TOO;
+		if (!ignored)
+			dir.flags |= DIR_SHOW_IGNORED_TOO_MODE_MATCHING;
+
+		/*
+		 * Let the fill_directory() machinery know that we aren't
+		 * just recursing to collect the ignored files; we want all
+		 * the untracked ones so that we can delete them.  (Note:
+		 * we could also set DIR_KEEP_UNTRACKED_CONTENTS when
+		 * ignored_only is true, since DIR_KEEP_UNTRACKED_CONTENTS
+		 * only has effect in combination with DIR_SHOW_IGNORED_TOO.  It makes
+		 * the code clearer to exclude it, though.
+		 */
+		dir.flags |= DIR_KEEP_UNTRACKED_CONTENTS;
+	}
 
 	if (read_cache() < 0)
 		die(_("index file corrupt"));
 
-	if (!ignored)
-		setup_standard_excludes(&dir);
-
 	pl = add_pattern_list(&dir, EXC_CMDL, "--exclude option");
 	for (i = 0; i < exclude_list.nr; i++)
 		add_pattern(exclude_list.items[i].string, "", 0, pl, -(i+1));
diff --git a/builtin/diff.c b/builtin/diff.c
index 8537b17..8c36da0 100644
--- a/builtin/diff.c
+++ b/builtin/diff.c
@@ -6,6 +6,7 @@
 #define USE_THE_INDEX_COMPATIBILITY_MACROS
 #include "cache.h"
 #include "config.h"
+#include "ewah/ewok.h"
 #include "lockfile.h"
 #include "color.h"
 #include "commit.h"
@@ -23,7 +24,13 @@
 #define DIFF_NO_INDEX_IMPLICIT 2
 
 static const char builtin_diff_usage[] =
-"git diff [<options>] [<commit> [<commit>]] [--] [<path>...]";
+"git diff [<options>] [<commit>] [--] [<path>...]\n"
+"   or: git diff [<options>] --cached [<commit>] [--] [<path>...]\n"
+"   or: git diff [<options>] <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"
+COMMON_DIFF_OPTIONS_HELP;
 
 static const char *blob_path(struct object_array_entry *entry)
 {
@@ -254,6 +261,108 @@
 	return run_diff_files(revs, options);
 }
 
+struct symdiff {
+	struct bitmap *skip;
+	int warn;
+	const char *base, *left, *right;
+};
+
+/*
+ * Check for symmetric-difference arguments, and if present, arrange
+ * everything we need to know to handle them correctly.  As a bonus,
+ * weed out all bogus range-based revision specifications, e.g.,
+ * "git diff A..B C..D" or "git diff A..B C" get rejected.
+ *
+ * For an actual symmetric diff, *symdiff is set this way:
+ *
+ *  - its skip is non-NULL and marks *all* rev->pending.objects[i]
+ *    indices that the caller should ignore (extra merge bases, of
+ *    which there might be many, and A in A...B).  Note that the
+ *    chosen merge base and right side are NOT marked.
+ *  - warn is set if there are multiple merge bases.
+ *  - base, left, and right point to the names to use in a
+ *    warning about multiple merge bases.
+ *
+ * If there is no symmetric diff argument, sym->skip is NULL and
+ * sym->warn is cleared.  The remaining fields are not set.
+ */
+static void symdiff_prepare(struct rev_info *rev, struct symdiff *sym)
+{
+	int i, is_symdiff = 0, basecount = 0, othercount = 0;
+	int lpos = -1, rpos = -1, basepos = -1;
+	struct bitmap *map = NULL;
+
+	/*
+	 * Use the whence fields to find merge bases and left and
+	 * right parts of symmetric difference, so that we do not
+	 * depend on the order that revisions are parsed.  If there
+	 * are any revs that aren't from these sources, we have a
+	 * "git diff C A...B" or "git diff A...B C" case.  Or we
+	 * could even get "git diff A...B C...E", for instance.
+	 *
+	 * If we don't have just one merge base, we pick one
+	 * at random.
+	 *
+	 * NB: REV_CMD_LEFT, REV_CMD_RIGHT are also used for A..B,
+	 * so we must check for SYMMETRIC_LEFT too.  The two arrays
+	 * rev->pending.objects and rev->cmdline.rev are parallel.
+	 */
+	for (i = 0; i < rev->cmdline.nr; i++) {
+		struct object *obj = rev->pending.objects[i].item;
+		switch (rev->cmdline.rev[i].whence) {
+		case REV_CMD_MERGE_BASE:
+			if (basepos < 0)
+				basepos = i;
+			basecount++;
+			break;		/* do mark all bases */
+		case REV_CMD_LEFT:
+			if (lpos >= 0)
+				usage(builtin_diff_usage);
+			lpos = i;
+			if (obj->flags & SYMMETRIC_LEFT) {
+				is_symdiff = 1;
+				break;	/* do mark A */
+			}
+			continue;
+		case REV_CMD_RIGHT:
+			if (rpos >= 0)
+				usage(builtin_diff_usage);
+			rpos = i;
+			continue;	/* don't mark B */
+		case REV_CMD_PARENTS_ONLY:
+		case REV_CMD_REF:
+		case REV_CMD_REV:
+			othercount++;
+			continue;
+		}
+		if (map == NULL)
+			map = bitmap_new();
+		bitmap_set(map, i);
+	}
+
+	/*
+	 * Forbid any additional revs for both A...B and A..B.
+	 */
+	if (lpos >= 0 && othercount > 0)
+		usage(builtin_diff_usage);
+
+	if (!is_symdiff) {
+		bitmap_free(map);
+		sym->warn = 0;
+		sym->skip = NULL;
+		return;
+	}
+
+	sym->left = rev->pending.objects[lpos].name;
+	sym->right = rev->pending.objects[rpos].name;
+	sym->base = rev->pending.objects[basepos].name;
+	if (basecount == 0)
+		die(_("%s...%s: no merge base"), sym->left, sym->right);
+	bitmap_unset(map, basepos);	/* unmark the base we want */
+	sym->warn = basecount > 1;
+	sym->skip = map;
+}
+
 int cmd_diff(int argc, const char **argv, const char *prefix)
 {
 	int i;
@@ -263,19 +372,29 @@
 	struct object_array_entry *blob[2];
 	int nongit = 0, no_index = 0;
 	int result = 0;
+	struct symdiff sdiff;
 
 	/*
 	 * We could get N tree-ish in the rev.pending_objects list.
-	 * Also there could be M blobs there, and P pathspecs.
+	 * Also there could be M blobs there, and P pathspecs. --cached may
+	 * also be present.
 	 *
 	 * N=0, M=0:
-	 *	cache vs files (diff-files)
+	 *      cache vs files (diff-files)
+	 *
+	 * N=0, M=0, --cached:
+	 *      HEAD vs cache (diff-index --cached)
+	 *
 	 * N=0, M=2:
 	 *      compare two random blobs.  P must be zero.
+	 *
 	 * N=0, M=1, P=1:
-	 *	compare a blob with a working tree file.
+	 *      compare a blob with a working tree file.
 	 *
 	 * N=1, M=0:
+	 *      tree vs files (diff-index)
+	 *
+	 * N=1, M=0, --cached:
 	 *      tree vs cache (diff-index --cached)
 	 *
 	 * N=2, M=0:
@@ -382,6 +501,7 @@
 		}
 	}
 
+	symdiff_prepare(&rev, &sdiff);
 	for (i = 0; i < rev.pending.nr; i++) {
 		struct object_array_entry *entry = &rev.pending.objects[i];
 		struct object *obj = entry->item;
@@ -396,6 +516,8 @@
 			obj = &get_commit_tree(((struct commit *)obj))->object;
 
 		if (obj->type == OBJ_TREE) {
+			if (sdiff.skip && bitmap_get(sdiff.skip, i))
+				continue;
 			obj->flags |= flags;
 			add_object_array(obj, name, &ent);
 		} else if (obj->type == OBJ_BLOB) {
@@ -437,21 +559,12 @@
 		usage(builtin_diff_usage);
 	else if (ent.nr == 1)
 		result = builtin_diff_index(&rev, argc, argv);
-	else if (ent.nr == 2)
+	else if (ent.nr == 2) {
+		if (sdiff.warn)
+			warning(_("%s...%s: multiple merge bases, using %s"),
+				sdiff.left, sdiff.right, sdiff.base);
 		result = builtin_diff_tree(&rev, argc, argv,
 					   &ent.objects[0], &ent.objects[1]);
-	else if (ent.objects[0].item->flags & UNINTERESTING) {
-		/*
-		 * diff A...B where there is at least one merge base
-		 * between A and B.  We have ent.objects[0] ==
-		 * merge-base, ent.objects[ents-2] == A, and
-		 * ent.objects[ents-1] == B.  Show diff between the
-		 * base and B.  Note that we pick one merge base at
-		 * random if there are more than one.
-		 */
-		result = builtin_diff_tree(&rev, argc, argv,
-					   &ent.objects[0],
-					   &ent.objects[ent.nr-1]);
 	} else
 		result = builtin_diff_combined(&rev, argc, argv,
 					       ent.objects, ent.nr);
diff --git a/builtin/fetch-pack.c b/builtin/fetch-pack.c
index 94b0c89..bbb5c96 100644
--- a/builtin/fetch-pack.c
+++ b/builtin/fetch-pack.c
@@ -48,8 +48,8 @@
 	struct ref **sought = NULL;
 	int nr_sought = 0, alloc_sought = 0;
 	int fd[2];
-	char *pack_lockfile = NULL;
-	char **pack_lockfile_ptr = NULL;
+	struct string_list pack_lockfiles = STRING_LIST_INIT_DUP;
+	struct string_list *pack_lockfiles_ptr = NULL;
 	struct child_process *conn;
 	struct fetch_pack_args args;
 	struct oid_array shallow = OID_ARRAY_INIT;
@@ -134,7 +134,7 @@
 		}
 		if (!strcmp("--lock-pack", arg)) {
 			args.lock_pack = 1;
-			pack_lockfile_ptr = &pack_lockfile;
+			pack_lockfiles_ptr = &pack_lockfiles;
 			continue;
 		}
 		if (!strcmp("--check-self-contained-and-connected", arg)) {
@@ -235,10 +235,15 @@
 	}
 
 	ref = fetch_pack(&args, fd, ref, sought, nr_sought,
-			 &shallow, pack_lockfile_ptr, version);
-	if (pack_lockfile) {
-		printf("lock %s\n", pack_lockfile);
+			 &shallow, pack_lockfiles_ptr, version);
+	if (pack_lockfiles.nr) {
+		int i;
+
+		printf("lock %s\n", pack_lockfiles.items[0].string);
 		fflush(stdout);
+		for (i = 1; i < pack_lockfiles.nr; i++)
+			warning(_("Lockfile created but not reported: %s"),
+				pack_lockfiles.items[i].string);
 	}
 	if (args.check_self_contained_and_connected &&
 	    args.self_contained_and_connected) {
diff --git a/builtin/fetch.c b/builtin/fetch.c
index da11165ce..82ac4be 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -1795,9 +1795,6 @@
 	if (depth || deepen_since || deepen_not.nr)
 		deepen = 1;
 
-	if (filter_options.choice && !has_promisor_remote())
-		die("--filter can only be used when extensions.partialClone is set");
-
 	if (all) {
 		if (argc == 1)
 			die(_("fetch --all does not take a repository argument"));
diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index c5b433a..7016b28 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -117,6 +117,8 @@
 
 static struct list_objects_filter_options filter_options;
 
+static struct string_list uri_protocols = STRING_LIST_INIT_NODUP;
+
 enum missing_action {
 	MA_ERROR = 0,      /* fail if any missing objects are encountered */
 	MA_ALLOW_ANY,      /* silently allow ALL missing objects */
@@ -125,6 +127,15 @@
 static enum missing_action arg_missing_action;
 static show_object_fn fn_show_object;
 
+struct configured_exclusion {
+	struct oidmap_entry e;
+	char *pack_hash_hex;
+	char *uri;
+};
+static struct oidmap configured_exclusions;
+
+static struct oidset excluded_by_config;
+
 /*
  * stats
  */
@@ -969,6 +980,25 @@
 	unuse_pack(&w_curs);
 }
 
+static void write_excluded_by_configs(void)
+{
+	struct oidset_iter iter;
+	const struct object_id *oid;
+
+	oidset_iter_init(&excluded_by_config, &iter);
+	while ((oid = oidset_iter_next(&iter))) {
+		struct configured_exclusion *ex =
+			oidmap_get(&configured_exclusions, oid);
+
+		if (!ex)
+			BUG("configured exclusion wasn't configured");
+		write_in_full(1, ex->pack_hash_hex, strlen(ex->pack_hash_hex));
+		write_in_full(1, " ", 1);
+		write_in_full(1, ex->uri, strlen(ex->uri));
+		write_in_full(1, "\n", 1);
+	}
+}
+
 static const char no_split_warning[] = N_(
 "disabling bitmap writing, packs are split due to pack.packSizeLimit"
 );
@@ -1266,6 +1296,25 @@
 		}
 	}
 
+	if (uri_protocols.nr) {
+		struct configured_exclusion *ex =
+			oidmap_get(&configured_exclusions, oid);
+		int i;
+		const char *p;
+
+		if (ex) {
+			for (i = 0; i < uri_protocols.nr; i++) {
+				if (skip_prefix(ex->uri,
+						uri_protocols.items[i].string,
+						&p) &&
+				    *p == ':') {
+					oidset_insert(&excluded_by_config, oid);
+					return 0;
+				}
+			}
+		}
+	}
+
 	return 1;
 }
 
@@ -2864,6 +2913,29 @@
 			    pack_idx_opts.version);
 		return 0;
 	}
+	if (!strcmp(k, "uploadpack.blobpackfileuri")) {
+		struct configured_exclusion *ex = xmalloc(sizeof(*ex));
+		const char *oid_end, *pack_end;
+		/*
+		 * Stores the pack hash. This is not a true object ID, but is
+		 * of the same form.
+		 */
+		struct object_id pack_hash;
+
+		if (parse_oid_hex(v, &ex->e.oid, &oid_end) ||
+		    *oid_end != ' ' ||
+		    parse_oid_hex(oid_end + 1, &pack_hash, &pack_end) ||
+		    *pack_end != ' ')
+			die(_("value of uploadpack.blobpackfileuri must be "
+			      "of the form '<object-hash> <pack-hash> <uri>' (got '%s')"), v);
+		if (oidmap_get(&configured_exclusions, &ex->e.oid))
+			die(_("object already configured in another "
+			      "uploadpack.blobpackfileuri (got '%s')"), v);
+		ex->pack_hash_hex = xcalloc(1, pack_end - oid_end);
+		memcpy(ex->pack_hash_hex, oid_end + 1, pack_end - oid_end - 1);
+		ex->uri = xstrdup(pack_end + 1);
+		oidmap_put(&configured_exclusions, ex);
+	}
 	return git_default_config(k, v, cb);
 }
 
@@ -3462,6 +3534,9 @@
 			 N_("do not pack objects in promisor packfiles")),
 		OPT_BOOL(0, "delta-islands", &use_delta_islands,
 			 N_("respect islands during delta compression")),
+		OPT_STRING_LIST(0, "uri-protocol", &uri_protocols,
+				N_("protocol"),
+				N_("exclude any configured uploadpack.blobpackfileuri with this protocol")),
 		OPT_END(),
 	};
 
@@ -3650,6 +3725,7 @@
 	}
 
 	trace2_region_enter("pack-objects", "write-pack-file", the_repository);
+	write_excluded_by_configs();
 	write_pack_file();
 	trace2_region_leave("pack-objects", "write-pack-file", the_repository);
 
diff --git a/builtin/pull.c b/builtin/pull.c
index 00e5857..8e6572d 100644
--- a/builtin/pull.c
+++ b/builtin/pull.c
@@ -1031,6 +1031,7 @@
 				ran_ff = 1;
 				ret = run_merge();
 			}
+			free_commit_list(list);
 		}
 		if (!ran_ff)
 			ret = run_rebase(&curr_head, merge_heads.oid, &rebase_fork_point);
diff --git a/builtin/sparse-checkout.c b/builtin/sparse-checkout.c
index 595463b..4003f4d 100644
--- a/builtin/sparse-checkout.c
+++ b/builtin/sparse-checkout.c
@@ -253,6 +253,8 @@
 {
 	const char *config_path;
 
+	if (upgrade_repository_format(1) < 0)
+		die(_("unable to upgrade repository format to enable worktreeConfig"));
 	if (git_config_set_gently("extensions.worktreeConfig", "true")) {
 		error(_("failed to set extensions.worktreeConfig setting"));
 		return 1;
diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index 46c03d2..59c1e12 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -2277,6 +2277,49 @@
 	return 0;
 }
 
+static int module_set_branch(int argc, const char **argv, const char *prefix)
+{
+	int opt_default = 0, ret;
+	const char *opt_branch = NULL;
+	const char *path;
+	char *config_name;
+
+	/*
+	 * We accept the `quiet` option for uniformity across subcommands,
+	 * though there is nothing to make less verbose in this subcommand.
+	 */
+	struct option options[] = {
+		OPT_NOOP_NOARG('q', "quiet"),
+		OPT_BOOL('d', "default", &opt_default,
+			N_("set the default tracking branch to master")),
+		OPT_STRING('b', "branch", &opt_branch, N_("branch"),
+			N_("set the default tracking branch")),
+		OPT_END()
+	};
+	const char *const usage[] = {
+		N_("git submodule--helper set-branch [-q|--quiet] (-d|--default) <path>"),
+		N_("git submodule--helper set-branch [-q|--quiet] (-b|--branch) <branch> <path>"),
+		NULL
+	};
+
+	argc = parse_options(argc, argv, prefix, options, usage, 0);
+
+	if (!opt_branch && !opt_default)
+		die(_("--branch or --default required"));
+
+	if (opt_branch && opt_default)
+		die(_("--branch and --default are mutually exclusive"));
+
+	if (argc != 1 || !(path = argv[0]))
+		usage_with_options(usage, options);
+
+	config_name = xstrfmt("submodule.%s.branch", path);
+	ret = config_set_in_gitmodules_file_gently(config_name, opt_branch);
+
+	free(config_name);
+	return !!ret;
+}
+
 #define SUPPORT_SUPER_PREFIX (1<<0)
 
 struct cmd_struct {
@@ -2308,6 +2351,7 @@
 	{"check-name", check_name, 0},
 	{"config", module_config, 0},
 	{"set-url", module_set_url, 0},
+	{"set-branch", module_set_branch, 0},
 };
 
 int cmd_submodule__helper(int argc, const char **argv, const char *prefix)
diff --git a/builtin/worktree.c b/builtin/worktree.c
index d99db35..1238b6b 100644
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -67,7 +67,12 @@
 	rmdir(git_path("worktrees")); /* ignore failed removal */
 }
 
-static int prune_worktree(const char *id, struct strbuf *reason)
+/*
+ * Return true if worktree entry should be pruned, along with the reason for
+ * pruning. Otherwise, return false and the worktree's path, or NULL if it
+ * cannot be determined. Caller is responsible for freeing returned path.
+ */
+static int should_prune_worktree(const char *id, struct strbuf *reason, char **wtpath)
 {
 	struct stat st;
 	char *path;
@@ -75,20 +80,21 @@
 	size_t len;
 	ssize_t read_result;
 
+	*wtpath = NULL;
 	if (!is_directory(git_path("worktrees/%s", id))) {
-		strbuf_addf(reason, _("Removing worktrees/%s: not a valid directory"), id);
+		strbuf_addstr(reason, _("not a valid directory"));
 		return 1;
 	}
 	if (file_exists(git_path("worktrees/%s/locked", id)))
 		return 0;
 	if (stat(git_path("worktrees/%s/gitdir", id), &st)) {
-		strbuf_addf(reason, _("Removing worktrees/%s: gitdir file does not exist"), id);
+		strbuf_addstr(reason, _("gitdir file does not exist"));
 		return 1;
 	}
 	fd = open(git_path("worktrees/%s/gitdir", id), O_RDONLY);
 	if (fd < 0) {
-		strbuf_addf(reason, _("Removing worktrees/%s: unable to read gitdir file (%s)"),
-			    id, strerror(errno));
+		strbuf_addf(reason, _("unable to read gitdir file (%s)"),
+			    strerror(errno));
 		return 1;
 	}
 	len = xsize_t(st.st_size);
@@ -96,8 +102,8 @@
 
 	read_result = read_in_full(fd, path, len);
 	if (read_result < 0) {
-		strbuf_addf(reason, _("Removing worktrees/%s: unable to read gitdir file (%s)"),
-			    id, strerror(errno));
+		strbuf_addf(reason, _("unable to read gitdir file (%s)"),
+			    strerror(errno));
 		close(fd);
 		free(path);
 		return 1;
@@ -106,53 +112,103 @@
 
 	if (read_result != len) {
 		strbuf_addf(reason,
-			    _("Removing worktrees/%s: short read (expected %"PRIuMAX" bytes, read %"PRIuMAX")"),
-			    id, (uintmax_t)len, (uintmax_t)read_result);
+			    _("short read (expected %"PRIuMAX" bytes, read %"PRIuMAX")"),
+			    (uintmax_t)len, (uintmax_t)read_result);
 		free(path);
 		return 1;
 	}
 	while (len && (path[len - 1] == '\n' || path[len - 1] == '\r'))
 		len--;
 	if (!len) {
-		strbuf_addf(reason, _("Removing worktrees/%s: invalid gitdir file"), id);
+		strbuf_addstr(reason, _("invalid gitdir file"));
 		free(path);
 		return 1;
 	}
 	path[len] = '\0';
 	if (!file_exists(path)) {
-		free(path);
 		if (stat(git_path("worktrees/%s/index", id), &st) ||
 		    st.st_mtime <= expire) {
-			strbuf_addf(reason, _("Removing worktrees/%s: gitdir file points to non-existent location"), id);
+			strbuf_addstr(reason, _("gitdir file points to non-existent location"));
+			free(path);
 			return 1;
 		} else {
+			*wtpath = path;
 			return 0;
 		}
 	}
-	free(path);
+	*wtpath = path;
 	return 0;
 }
 
+static void prune_worktree(const char *id, const char *reason)
+{
+	if (show_only || verbose)
+		printf_ln(_("Removing %s/%s: %s"), "worktrees", id, reason);
+	if (!show_only)
+		delete_git_dir(id);
+}
+
+static int prune_cmp(const void *a, const void *b)
+{
+	const struct string_list_item *x = a;
+	const struct string_list_item *y = b;
+	int c;
+
+	if ((c = fspathcmp(x->string, y->string)))
+	    return c;
+	/*
+	 * paths same; prune_dupes() removes all but the first worktree entry
+	 * having the same path, so sort main worktree ('util' is NULL) above
+	 * linked worktrees ('util' not NULL) since main worktree can't be
+	 * removed
+	 */
+	if (!x->util)
+		return -1;
+	if (!y->util)
+		return 1;
+	/* paths same; sort by .git/worktrees/<id> */
+	return strcmp(x->util, y->util);
+}
+
+static void prune_dups(struct string_list *l)
+{
+	int i;
+
+	QSORT(l->items, l->nr, prune_cmp);
+	for (i = 1; i < l->nr; i++) {
+		if (!fspathcmp(l->items[i].string, l->items[i - 1].string))
+			prune_worktree(l->items[i].util, "duplicate entry");
+	}
+}
+
 static void prune_worktrees(void)
 {
 	struct strbuf reason = STRBUF_INIT;
+	struct strbuf main_path = STRBUF_INIT;
+	struct string_list kept = STRING_LIST_INIT_NODUP;
 	DIR *dir = opendir(git_path("worktrees"));
 	struct dirent *d;
 	if (!dir)
 		return;
 	while ((d = readdir(dir)) != NULL) {
+		char *path;
 		if (is_dot_or_dotdot(d->d_name))
 			continue;
 		strbuf_reset(&reason);
-		if (!prune_worktree(d->d_name, &reason))
-			continue;
-		if (show_only || verbose)
-			printf("%s\n", reason.buf);
-		if (show_only)
-			continue;
-		delete_git_dir(d->d_name);
+		if (should_prune_worktree(d->d_name, &reason, &path))
+			prune_worktree(d->d_name, reason.buf);
+		else if (path)
+			string_list_append(&kept, path)->util = xstrdup(d->d_name);
 	}
 	closedir(dir);
+
+	strbuf_add_absolute_path(&main_path, get_git_common_dir());
+	/* massage main worktree absolute path to match 'gitdir' content */
+	strbuf_strip_suffix(&main_path, "/.");
+	string_list_append(&kept, strbuf_detach(&main_path, NULL));
+	prune_dups(&kept);
+	string_list_clear(&kept, 1);
+
 	if (!show_only)
 		delete_worktrees_dir_if_empty();
 	strbuf_release(&reason);
@@ -224,34 +280,33 @@
 	return name;
 }
 
-static void validate_worktree_add(const char *path, const struct add_opts *opts)
+/* check that path is viable location for worktree */
+static void check_candidate_path(const char *path,
+				 int force,
+				 struct worktree **worktrees,
+				 const char *cmd)
 {
-	struct worktree **worktrees;
 	struct worktree *wt;
 	int locked;
 
 	if (file_exists(path) && !is_empty_dir(path))
 		die(_("'%s' already exists"), path);
 
-	worktrees = get_worktrees(0);
 	wt = find_worktree_by_path(worktrees, path);
 	if (!wt)
-		goto done;
+		return;
 
 	locked = !!worktree_lock_reason(wt);
-	if ((!locked && opts->force) || (locked && opts->force > 1)) {
+	if ((!locked && force) || (locked && force > 1)) {
 		if (delete_git_dir(wt->id))
-		    die(_("unable to re-add worktree '%s'"), path);
-		goto done;
+		    die(_("unusable worktree destination '%s'"), path);
+		return;
 	}
 
 	if (locked)
-		die(_("'%s' is a missing but locked worktree;\nuse 'add -f -f' to override, or 'unlock' and 'prune' or 'remove' to clear"), path);
+		die(_("'%s' is a missing but locked worktree;\nuse '%s -f -f' to override, or 'unlock' and 'prune' or 'remove' to clear"), cmd, path);
 	else
-		die(_("'%s' is a missing but already registered worktree;\nuse 'add -f' to override, or 'prune' or 'remove' to clear"), path);
-
-done:
-	free_worktrees(worktrees);
+		die(_("'%s' is a missing but already registered worktree;\nuse '%s -f' to override, or 'prune' or 'remove' to clear"), cmd, path);
 }
 
 static int add_worktree(const char *path, const char *refname,
@@ -268,8 +323,12 @@
 	struct commit *commit = NULL;
 	int is_branch = 0;
 	struct strbuf sb_name = STRBUF_INIT;
+	struct worktree **worktrees;
 
-	validate_worktree_add(path, opts);
+	worktrees = get_worktrees(0);
+	check_candidate_path(path, opts->force, worktrees, "add");
+	free_worktrees(worktrees);
+	worktrees = NULL;
 
 	/* is 'refname' a branch or commit? */
 	if (!opts->detach && !strbuf_check_branch_ref(&symref, refname) &&
@@ -804,8 +863,7 @@
 		strbuf_trim_trailing_dir_sep(&dst);
 		strbuf_addstr(&dst, sep);
 	}
-	if (file_exists(dst.buf))
-		die(_("target '%s' already exists"), dst.buf);
+	check_candidate_path(dst.buf, force, worktrees, "move");
 
 	validate_no_submodules(wt);
 
diff --git a/cache.h b/cache.h
index 0f0485e..e5885cc 100644
--- a/cache.h
+++ b/cache.h
@@ -1042,6 +1042,7 @@
 	int worktree_config;
 	int is_bare;
 	int hash_algo;
+	int has_extensions;
 	char *work_tree;
 	struct string_list unknown_extensions;
 };
diff --git a/commit-reach.c b/commit-reach.c
index 4ca7e70..1761217 100644
--- a/commit-reach.c
+++ b/commit-reach.c
@@ -283,7 +283,9 @@
 /*
  * Is "commit" a descendant of one of the elements on the "with_commit" list?
  */
-int is_descendant_of(struct commit *commit, struct commit_list *with_commit)
+static int repo_is_descendant_of(struct repository *r,
+				 struct commit *commit,
+				 struct commit_list *with_commit)
 {
 	if (!with_commit)
 		return 1;
@@ -301,13 +303,18 @@
 
 			other = with_commit->item;
 			with_commit = with_commit->next;
-			if (in_merge_bases(other, commit))
+			if (repo_in_merge_bases_many(r, other, 1, &commit))
 				return 1;
 		}
 		return 0;
 	}
 }
 
+int is_descendant_of(struct commit *commit, struct commit_list *with_commit)
+{
+	return repo_is_descendant_of(the_repository, commit, with_commit);
+}
+
 /*
  * Is "commit" an ancestor of one of the "references"?
  */
@@ -348,7 +355,15 @@
 			struct commit *commit,
 			struct commit *reference)
 {
-	return repo_in_merge_bases_many(r, commit, 1, &reference);
+	int res;
+	struct commit_list *list = NULL;
+	struct commit_list **next = &list;
+
+	next = commit_list_append(commit, next);
+	res = repo_is_descendant_of(r, reference, list);
+	free_commit_list(list);
+
+	return res;
 }
 
 struct commit_list *reduce_heads(struct commit_list *heads)
@@ -396,6 +411,7 @@
 	struct object *o;
 	struct commit *old_commit, *new_commit;
 	struct commit_list *old_commit_list = NULL;
+	int ret;
 
 	/*
 	 * Both new_commit and old_commit must be commit-ish and new_commit is descendant of
@@ -417,7 +433,9 @@
 		return 0;
 
 	commit_list_insert(old_commit, &old_commit_list);
-	return is_descendant_of(new_commit, old_commit_list);
+	ret = is_descendant_of(new_commit, old_commit_list);
+	free_commit_list(old_commit_list);
+	return ret;
 }
 
 /*
diff --git a/connected.c b/connected.c
index 3135b71..937b4ba 100644
--- a/connected.c
+++ b/connected.c
@@ -43,10 +43,12 @@
 
 	if (transport && transport->smart_options &&
 	    transport->smart_options->self_contained_and_connected &&
-	    transport->pack_lockfile &&
-	    strip_suffix(transport->pack_lockfile, ".keep", &base_len)) {
+	    transport->pack_lockfiles.nr == 1 &&
+	    strip_suffix(transport->pack_lockfiles.items[0].string,
+			 ".keep", &base_len)) {
 		struct strbuf idx_file = STRBUF_INIT;
-		strbuf_add(&idx_file, transport->pack_lockfile, base_len);
+		strbuf_add(&idx_file, transport->pack_lockfiles.items[0].string,
+			   base_len);
 		strbuf_addstr(&idx_file, ".idx");
 		new_pack = add_packed_git(idx_file.buf, idx_file.len, 1);
 		strbuf_release(&idx_file);
diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index 4b59004..de5d0fb 100644
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -301,6 +301,19 @@
 	COMPREPLY=($1)
 }
 
+# Similar to __gitcomp_direct, but appends to COMPREPLY instead.
+# Callers must take care of providing only words that match the current word
+# to be completed and adding any prefix and/or suffix (trailing space!), if
+# necessary.
+# 1: List of newline-separated matching completion words, complete with
+#    prefix and suffix.
+__gitcomp_direct_append ()
+{
+	local IFS=$'\n'
+
+	COMPREPLY+=($1)
+}
+
 __gitcompappend ()
 {
 	local x i=${#COMPREPLY[@]}
@@ -611,6 +624,19 @@
 			"refs/heads/$cur_*" "refs/heads/$cur_*/**"
 }
 
+# Lists branches from remote repositories.
+# 1: A prefix to be added to each listed branch (optional).
+# 2: List only branches matching this word (optional; list all branches if
+#    unset or empty).
+# 3: A suffix to be appended to each listed branch (optional).
+__git_remote_heads ()
+{
+	local pfx="${1-}" cur_="${2-}" sfx="${3-}"
+
+	__git for-each-ref --format="${pfx//\%/%%}%(refname:strip=2)$sfx" \
+			"refs/remotes/$cur_*" "refs/remotes/$cur_*/**"
+}
+
 # Lists tags from the local repository.
 # Accepts the same positional parameters as __git_heads() above.
 __git_tags ()
@@ -621,6 +647,26 @@
 			"refs/tags/$cur_*" "refs/tags/$cur_*/**"
 }
 
+# List unique branches from refs/remotes used for 'git checkout' and 'git
+# switch' tracking DWIMery.
+# 1: A prefix to be added to each listed branch (optional)
+# 2: List only branches matching this word (optional; list all branches if
+#    unset or empty).
+# 3: A suffix to be appended to each listed branch (optional).
+__git_dwim_remote_heads ()
+{
+	local pfx="${1-}" cur_="${2-}" sfx="${3-}"
+	local fer_pfx="${pfx//\%/%%}" # "escape" for-each-ref format specifiers
+
+	# employ the heuristic used by git checkout and git switch
+	# Try to find a remote branch that cur_es the completion word
+	# but only output if the branch name is unique
+	__git for-each-ref --format="$fer_pfx%(refname:strip=3)$sfx" \
+		--sort="refname:strip=3" \
+		"refs/remotes/*/$cur_*" "refs/remotes/*/$cur_*/**" | \
+	uniq -u
+}
+
 # Lists refs from the local (by default) or from a remote repository.
 # It accepts 0, 1 or 2 arguments:
 # 1: The remote to list refs from (optional; ignored, if set but empty).
@@ -696,13 +742,7 @@
 		__git_dir="$dir" __git for-each-ref --format="$fer_pfx%($format)$sfx" \
 			"${refs[@]}"
 		if [ -n "$track" ]; then
-			# employ the heuristic used by git checkout
-			# Try to find a remote branch that matches the completion word
-			# but only output if the branch name is unique
-			__git for-each-ref --format="$fer_pfx%(refname:strip=3)$sfx" \
-				--sort="refname:strip=3" \
-				"refs/remotes/*/$match*" "refs/remotes/*/$match*/**" | \
-			uniq -u
+			__git_dwim_remote_heads "$pfx" "$match" "$sfx"
 		fi
 		return
 	fi
@@ -749,29 +789,51 @@
 # Usage: __git_complete_refs [<option>]...
 # --remote=<remote>: The remote to list refs from, can be the name of a
 #                    configured remote, a path, or a URL.
-# --track: List unique remote branches for 'git checkout's tracking DWIMery.
+# --dwim: List unique remote branches for 'git switch's tracking DWIMery.
 # --pfx=<prefix>: A prefix to be added to each ref.
 # --cur=<word>: The current ref to be completed.  Defaults to the current
 #               word to be completed.
 # --sfx=<suffix>: A suffix to be appended to each ref instead of the default
 #                 space.
+# --mode=<mode>: What set of refs to complete, one of 'refs' (the default) to
+#                complete all refs, 'heads' to complete only branches, or
+#                'remote-heads' to complete only remote branches. Note that
+#                --remote is only compatible with --mode=refs.
 __git_complete_refs ()
 {
-	local remote track pfx cur_="$cur" sfx=" "
+	local remote dwim pfx cur_="$cur" sfx=" " mode="refs"
 
 	while test $# != 0; do
 		case "$1" in
 		--remote=*)	remote="${1##--remote=}" ;;
-		--track)	track="yes" ;;
+		--dwim)		dwim="yes" ;;
+		# --track is an old spelling of --dwim
+		--track)	dwim="yes" ;;
 		--pfx=*)	pfx="${1##--pfx=}" ;;
 		--cur=*)	cur_="${1##--cur=}" ;;
 		--sfx=*)	sfx="${1##--sfx=}" ;;
+		--mode=*)	mode="${1##--mode=}" ;;
 		*)		return 1 ;;
 		esac
 		shift
 	done
 
-	__gitcomp_direct "$(__git_refs "$remote" "$track" "$pfx" "$cur_" "$sfx")"
+	# complete references based on the specified mode
+	case "$mode" in
+		refs)
+			__gitcomp_direct "$(__git_refs "$remote" "" "$pfx" "$cur_" "$sfx")" ;;
+		heads)
+			__gitcomp_direct "$(__git_heads "$pfx" "$cur_" "$sfx")" ;;
+		remote-heads)
+			__gitcomp_direct "$(__git_remote_heads "$pfx" "$cur_" "$sfx")" ;;
+		*)
+			return 1 ;;
+	esac
+
+	# Append DWIM remote branch names if requested
+	if [ "$dwim" = "yes" ]; then
+		__gitcomp_direct_append "$(__git_dwim_remote_heads "$pfx" "$cur_" "$sfx")"
+	fi
 }
 
 # __git_refs2 requires 1 argument (to pass to __git_refs)
@@ -1102,6 +1164,40 @@
 	done
 }
 
+# Similar to __git_find_on_cmdline, except that it loops backwards and thus
+# prints the *last* word found. Useful for finding which of two options that
+# supersede each other came last, such as "--guess" and "--no-guess".
+#
+# Usage: __git_find_last_on_cmdline [<option>]... "<wordlist>"
+# --show-idx: Optionally show the index of the found word in the $words array.
+__git_find_last_on_cmdline ()
+{
+	local word c=$cword show_idx
+
+	while test $# -gt 1; do
+		case "$1" in
+		--show-idx)	show_idx=y ;;
+		*)		return 1 ;;
+		esac
+		shift
+	done
+	local wordlist="$1"
+
+	while [ $c -gt 1 ]; do
+		((c--))
+		for word in $wordlist; do
+			if [ "$word" = "${words[c]}" ]; then
+				if [ -n "$show_idx" ]; then
+					echo "$c $word"
+				else
+					echo "$word"
+				fi
+				return
+			fi
+		done
+	done
+}
+
 # Echo the value of an option set on the command line or config
 #
 # $1: short option name
@@ -1356,6 +1452,46 @@
 	esac
 }
 
+# Helper function to decide whether or not we should enable DWIM logic for
+# git-switch and git-checkout.
+#
+# To decide between the following rules in priority order
+# 1) the last provided of "--guess" or "--no-guess" explicitly enable or
+#    disable completion of DWIM logic respectively.
+# 2) If the --no-track option is provided, take this as a hint to disable the
+#    DWIM completion logic
+# 3) If GIT_COMPLETION_CHECKOUT_NO_GUESS is set, disable the DWIM completion
+#    logic, as requested by the user.
+# 4) Enable DWIM logic otherwise.
+#
+__git_checkout_default_dwim_mode ()
+{
+	local last_option dwim_opt="--dwim"
+
+	if [ "$GIT_COMPLETION_CHECKOUT_NO_GUESS" = "1" ]; then
+		dwim_opt=""
+	fi
+
+	# --no-track disables DWIM, but with lower priority than
+	# --guess/--no-guess
+	if [ -n "$(__git_find_on_cmdline "--no-track")" ]; then
+		dwim_opt=""
+	fi
+
+	# Find the last provided --guess or --no-guess
+	last_option="$(__git_find_last_on_cmdline "--guess --no-guess")"
+	case "$last_option" in
+		--guess)
+			dwim_opt="--dwim"
+			;;
+		--no-guess)
+			dwim_opt=""
+			;;
+	esac
+
+	echo "$dwim_opt"
+}
+
 _git_checkout ()
 {
 	__git_has_doubledash && return
@@ -1368,14 +1504,38 @@
 		__gitcomp_builtin checkout
 		;;
 	*)
-		# check if --track, --no-track, or --no-guess was specified
-		# if so, disable DWIM mode
-		local flags="--track --no-track --no-guess" track_opt="--track"
-		if [ "$GIT_COMPLETION_CHECKOUT_NO_GUESS" = "1" ] ||
-		   [ -n "$(__git_find_on_cmdline "$flags")" ]; then
-			track_opt=''
+		local dwim_opt="$(__git_checkout_default_dwim_mode)"
+		local prevword prevword="${words[cword-1]}"
+
+		case "$prevword" in
+			-b|-B|--orphan)
+				# Complete local branches (and DWIM branch
+				# remote branch names) for an option argument
+				# specifying a new branch name. This is for
+				# convenience, assuming new branches are
+				# possibly based on pre-existing branch names.
+				__git_complete_refs $dwim_opt --mode="heads"
+				return
+				;;
+			*)
+				;;
+		esac
+
+		# At this point, we've already handled special completion for
+		# the arguments to -b/-B, and --orphan. There are 3 main
+		# things left we can possibly complete:
+		# 1) a start-point for -b/-B, -d/--detach, or --orphan
+		# 2) a remote head, for --track
+		# 3) an arbitrary reference, possibly including DWIM names
+		#
+
+		if [ -n "$(__git_find_on_cmdline "-b -B -d --detach --orphan")" ]; then
+			__git_complete_refs --mode="refs"
+		elif [ -n "$(__git_find_on_cmdline "--track")" ]; then
+			__git_complete_refs --mode="remote-heads"
+		else
+			__git_complete_refs $dwim_opt --mode="refs"
 		fi
-		__git_complete_refs $track_opt
 		;;
 	esac
 }
@@ -2224,29 +2384,43 @@
 		__gitcomp_builtin switch
 		;;
 	*)
-		# check if --track, --no-track, or --no-guess was specified
-		# if so, disable DWIM mode
-		local track_opt="--track" only_local_ref=n
-		if [ "$GIT_COMPLETION_CHECKOUT_NO_GUESS" = "1" ] ||
-		   [ -n "$(__git_find_on_cmdline "--track --no-track --no-guess")" ]; then
-			track_opt=''
+		local dwim_opt="$(__git_checkout_default_dwim_mode)"
+		local prevword prevword="${words[cword-1]}"
+
+		case "$prevword" in
+			-c|-C|--orphan)
+				# Complete local branches (and DWIM branch
+				# remote branch names) for an option argument
+				# specifying a new branch name. This is for
+				# convenience, assuming new branches are
+				# possibly based on pre-existing branch names.
+				__git_complete_refs $dwim_opt --mode="heads"
+				return
+				;;
+			*)
+				;;
+		esac
+
+		# Unlike in git checkout, git switch --orphan does not take
+		# a start point. Thus we really have nothing to complete after
+		# the branch name.
+		if [ -n "$(__git_find_on_cmdline "--orphan")" ]; then
+			return
 		fi
-		# explicit --guess enables DWIM mode regardless of
-		# $GIT_COMPLETION_CHECKOUT_NO_GUESS
-		if [ -n "$(__git_find_on_cmdline "--guess")" ]; then
-			track_opt='--track'
-		fi
-		if [ -z "$(__git_find_on_cmdline "-d --detach")" ]; then
-			only_local_ref=y
+
+		# At this point, we've already handled special completion for
+		# -c/-C, and --orphan. There are 3 main things left to
+		# complete:
+		# 1) a start-point for -c/-C or -d/--detach
+		# 2) a remote head, for --track
+		# 3) a branch name, possibly including DWIM remote branches
+
+		if [ -n "$(__git_find_on_cmdline "-c -C -d --detach")" ]; then
+			__git_complete_refs --mode="refs"
+		elif [ -n "$(__git_find_on_cmdline "--track")" ]; then
+			__git_complete_refs --mode="remote-heads"
 		else
-			# --guess --detach is invalid combination, no
-			# dwim will be done when --detach is specified
-			track_opt=
-		fi
-		if [ $only_local_ref = y -a -z "$track_opt" ]; then
-			__gitcomp_direct "$(__git_heads "" "$cur" " ")"
-		else
-			__git_complete_refs $track_opt
+			__git_complete_refs $dwim_opt --mode="heads"
 		fi
 		;;
 	esac
diff --git a/dir.c b/dir.c
index 9ecd349..1045cc9 100644
--- a/dir.c
+++ b/dir.c
@@ -193,6 +193,10 @@
 	const char *prefix;
 	size_t prefix_len;
 
+	unsigned exclusive_flags = DIR_SHOW_IGNORED | DIR_SHOW_IGNORED_TOO;
+	if ((dir->flags & exclusive_flags) == exclusive_flags)
+		BUG("DIR_SHOW_IGNORED and DIR_SHOW_IGNORED_TOO are exclusive");
+
 	/*
 	 * Calculate common prefix for the pathspec, and
 	 * use that to optimize the directory walk
@@ -1836,7 +1840,7 @@
 	 * to recurse into untracked/ignored directories if either of the
 	 * following bits is set:
 	 *   - DIR_SHOW_IGNORED_TOO (because then we need to determine if
-	 *                           there are ignored directories below)
+	 *                           there are ignored entries below)
 	 *   - DIR_HIDE_EMPTY_DIRECTORIES (because we have to determine if
 	 *                                 the directory is empty)
 	 */
@@ -1854,10 +1858,11 @@
 		return path_excluded;
 
 	/*
-	 * If we have we don't want to know the all the paths under an
-	 * untracked or ignored directory, we still need to go into the
-	 * directory to determine if it is empty (because an empty directory
-	 * should be path_none instead of path_excluded or path_untracked).
+	 * Even if we don't want to know all the paths under an untracked or
+	 * ignored directory, we may still need to go into the directory to
+	 * determine if it is empty (because with DIR_HIDE_EMPTY_DIRECTORIES,
+	 * an empty directory should be path_none instead of path_excluded or
+	 * path_untracked).
 	 */
 	check_only = ((dir->flags & DIR_HIDE_EMPTY_DIRECTORIES) &&
 		      !(dir->flags & DIR_SHOW_IGNORED_TOO));
diff --git a/fetch-pack.c b/fetch-pack.c
index d8bbf45..acd55ba 100644
--- a/fetch-pack.c
+++ b/fetch-pack.c
@@ -38,6 +38,7 @@
 static struct shallow_lock shallow_lock;
 static const char *alternate_shallow_file;
 static struct strbuf fsck_msg_types = STRBUF_INIT;
+static struct string_list uri_protocols = STRING_LIST_INIT_DUP;
 
 /* Remember to update object flag allocation in object.h */
 #define COMPLETE	(1U << 0)
@@ -794,7 +795,8 @@
 }
 
 static int get_pack(struct fetch_pack_args *args,
-		    int xd[2], char **pack_lockfile,
+		    int xd[2], struct string_list *pack_lockfiles,
+		    int only_packfile,
 		    struct ref **sought, int nr_sought)
 {
 	struct async demux;
@@ -838,7 +840,7 @@
 	}
 
 	if (do_keep || args->from_promisor) {
-		if (pack_lockfile)
+		if (pack_lockfiles)
 			cmd.out = -1;
 		cmd_name = "index-pack";
 		argv_array_push(&cmd.args, cmd_name);
@@ -855,15 +857,22 @@
 					"--keep=fetch-pack %"PRIuMAX " on %s",
 					(uintmax_t)getpid(), hostname);
 		}
-		if (args->check_self_contained_and_connected)
+		if (only_packfile && args->check_self_contained_and_connected)
 			argv_array_push(&cmd.args, "--check-self-contained-and-connected");
+		else
+			/*
+			 * We cannot perform any connectivity checks because
+			 * not all packs have been downloaded; let the caller
+			 * have this responsibility.
+			 */
+			args->check_self_contained_and_connected = 0;
 		/*
 		 * If we're obtaining the filename of a lockfile, we'll use
 		 * that filename to write a .promisor file with more
 		 * information below. If not, we need index-pack to do it for
 		 * us.
 		 */
-		if (!(do_keep && pack_lockfile) && args->from_promisor)
+		if (!(do_keep && pack_lockfiles) && args->from_promisor)
 			argv_array_push(&cmd.args, "--promisor");
 	}
 	else {
@@ -899,8 +908,9 @@
 	cmd.git_cmd = 1;
 	if (start_command(&cmd))
 		die(_("fetch-pack: unable to fork off %s"), cmd_name);
-	if (do_keep && pack_lockfile) {
-		*pack_lockfile = index_pack_lockfile(cmd.out);
+	if (do_keep && pack_lockfiles) {
+		string_list_append_nodup(pack_lockfiles,
+					 index_pack_lockfile(cmd.out));
 		close(cmd.out);
 	}
 
@@ -922,8 +932,8 @@
 	 * Now that index-pack has succeeded, write the promisor file using the
 	 * obtained .keep filename if necessary
 	 */
-	if (do_keep && pack_lockfile && args->from_promisor)
-		write_promisor_file(*pack_lockfile, sought, nr_sought);
+	if (do_keep && pack_lockfiles && pack_lockfiles->nr && args->from_promisor)
+		write_promisor_file(pack_lockfiles->items[0].string, sought, nr_sought);
 
 	return 0;
 }
@@ -940,7 +950,7 @@
 				 const struct ref *orig_ref,
 				 struct ref **sought, int nr_sought,
 				 struct shallow_info *si,
-				 char **pack_lockfile)
+				 struct string_list *pack_lockfiles)
 {
 	struct repository *r = the_repository;
 	struct ref *ref = copy_ref_list(orig_ref);
@@ -1067,7 +1077,7 @@
 		alternate_shallow_file = setup_temporary_shallow(si->shallow);
 	else
 		alternate_shallow_file = NULL;
-	if (get_pack(args, fd, pack_lockfile, sought, nr_sought))
+	if (get_pack(args, fd, pack_lockfiles, 1, sought, nr_sought))
 		die(_("git fetch-pack: fetch failed."));
 
  all_done:
@@ -1221,6 +1231,26 @@
 		warning("filtering not recognized by server, ignoring");
 	}
 
+	if (server_supports_feature("fetch", "packfile-uris", 0)) {
+		int i;
+		struct strbuf to_send = STRBUF_INIT;
+
+		for (i = 0; i < uri_protocols.nr; i++) {
+			const char *s = uri_protocols.items[i].string;
+
+			if (!strcmp(s, "https") || !strcmp(s, "http")) {
+				if (to_send.len)
+					strbuf_addch(&to_send, ',');
+				strbuf_addstr(&to_send, s);
+			}
+		}
+		if (to_send.len) {
+			packet_buf_write(&req_buf, "packfile-uris %s",
+					 to_send.buf);
+			strbuf_release(&to_send);
+		}
+	}
+
 	/* add wants */
 	add_wants(args->no_dependents, wants, &req_buf);
 
@@ -1443,6 +1473,21 @@
 		die(_("error processing wanted refs: %d"), reader->status);
 }
 
+static void receive_packfile_uris(struct packet_reader *reader,
+				  struct string_list *uris)
+{
+	process_section_header(reader, "packfile-uris", 0);
+	while (packet_reader_read(reader) == PACKET_READ_NORMAL) {
+		if (reader->pktlen < the_hash_algo->hexsz ||
+		    reader->line[the_hash_algo->hexsz] != ' ')
+			die("expected '<hash> <uri>', got: %s\n", reader->line);
+
+		string_list_append(uris, reader->line);
+	}
+	if (reader->status != PACKET_READ_DELIM)
+		die("expected DELIM");
+}
+
 enum fetch_state {
 	FETCH_CHECK_LOCAL = 0,
 	FETCH_SEND_REQUEST,
@@ -1464,7 +1509,7 @@
 				    struct ref **sought, int nr_sought,
 				    struct oid_array *shallows,
 				    struct shallow_info *si,
-				    char **pack_lockfile)
+				    struct string_list *pack_lockfiles)
 {
 	struct repository *r = the_repository;
 	struct ref *ref = copy_ref_list(orig_ref);
@@ -1476,6 +1521,8 @@
 	struct fetch_negotiator negotiator_alloc;
 	struct fetch_negotiator *negotiator;
 	int seen_ack = 0;
+	struct string_list packfile_uris = STRING_LIST_INIT_DUP;
+	int i;
 
 	if (args->no_dependents) {
 		negotiator = NULL;
@@ -1569,9 +1616,12 @@
 			if (process_section_header(&reader, "wanted-refs", 1))
 				receive_wanted_refs(&reader, sought, nr_sought);
 
-			/* get the pack */
+			/* get the pack(s) */
+			if (process_section_header(&reader, "packfile-uris", 1))
+				receive_packfile_uris(&reader, &packfile_uris);
 			process_section_header(&reader, "packfile", 0);
-			if (get_pack(args, fd, pack_lockfile, sought, nr_sought))
+			if (get_pack(args, fd, pack_lockfiles,
+				     !packfile_uris.nr, sought, nr_sought))
 				die(_("git fetch-pack: fetch failed."));
 			do_check_stateless_delimiter(args, &reader);
 
@@ -1582,8 +1632,55 @@
 		}
 	}
 
+	for (i = 0; i < packfile_uris.nr; i++) {
+		struct child_process cmd = CHILD_PROCESS_INIT;
+		char packname[GIT_MAX_HEXSZ + 1];
+		const char *uri = packfile_uris.items[i].string +
+			the_hash_algo->hexsz + 1;
+
+		argv_array_push(&cmd.args, "http-fetch");
+		argv_array_pushf(&cmd.args, "--packfile=%.*s",
+				 (int) the_hash_algo->hexsz,
+				 packfile_uris.items[i].string);
+		argv_array_push(&cmd.args, uri);
+		cmd.git_cmd = 1;
+		cmd.no_stdin = 1;
+		cmd.out = -1;
+		if (start_command(&cmd))
+			die("fetch-pack: unable to spawn http-fetch");
+
+		if (read_in_full(cmd.out, packname, 5) < 0 ||
+		    memcmp(packname, "keep\t", 5))
+			die("fetch-pack: expected keep then TAB at start of http-fetch output");
+
+		if (read_in_full(cmd.out, packname,
+				 the_hash_algo->hexsz + 1) < 0 ||
+		    packname[the_hash_algo->hexsz] != '\n')
+			die("fetch-pack: expected hash then LF at end of http-fetch output");
+
+		packname[the_hash_algo->hexsz] = '\0';
+
+		close(cmd.out);
+
+		if (finish_command(&cmd))
+			die("fetch-pack: unable to finish http-fetch");
+
+		if (memcmp(packfile_uris.items[i].string, packname,
+			   the_hash_algo->hexsz))
+			die("fetch-pack: pack downloaded from %s does not match expected hash %.*s",
+			    uri, (int) the_hash_algo->hexsz,
+			    packfile_uris.items[i].string);
+
+		string_list_append_nodup(pack_lockfiles,
+					 xstrfmt("%s/pack/pack-%s.keep",
+						 get_object_directory(),
+						 packname));
+	}
+	string_list_clear(&packfile_uris, 0);
+
 	if (negotiator)
 		negotiator->release(negotiator);
+
 	oidset_clear(&common);
 	return ref;
 }
@@ -1620,6 +1717,14 @@
 	git_config_get_bool("repack.usedeltabaseoffset", &prefer_ofs_delta);
 	git_config_get_bool("fetch.fsckobjects", &fetch_fsck_objects);
 	git_config_get_bool("transfer.fsckobjects", &transfer_fsck_objects);
+	if (!uri_protocols.nr) {
+		char *str;
+
+		if (!git_config_get_string("fetch.uriprotocols", &str) && str) {
+			string_list_split(&uri_protocols, str, ',', -1);
+			free(str);
+		}
+	}
 
 	git_config(fetch_pack_config_cb, NULL);
 }
@@ -1772,7 +1877,7 @@
 		       const struct ref *ref,
 		       struct ref **sought, int nr_sought,
 		       struct oid_array *shallow,
-		       char **pack_lockfile,
+		       struct string_list *pack_lockfiles,
 		       enum protocol_version version)
 {
 	struct ref *ref_cpy;
@@ -1807,11 +1912,11 @@
 		memset(&si, 0, sizeof(si));
 		ref_cpy = do_fetch_pack_v2(args, fd, ref, sought, nr_sought,
 					   &shallows_scratch, &si,
-					   pack_lockfile);
+					   pack_lockfiles);
 	} else {
 		prepare_shallow_info(&si, shallow);
 		ref_cpy = do_fetch_pack(args, fd, ref, sought, nr_sought,
-					&si, pack_lockfile);
+					&si, pack_lockfiles);
 	}
 	reprepare_packed_git(the_repository);
 
diff --git a/fetch-pack.h b/fetch-pack.h
index 67f6842..85d1e39 100644
--- a/fetch-pack.h
+++ b/fetch-pack.h
@@ -83,7 +83,7 @@
 		       struct ref **sought,
 		       int nr_sought,
 		       struct oid_array *shallow,
-		       char **pack_lockfile,
+		       struct string_list *pack_lockfiles,
 		       enum protocol_version version);
 
 /*
diff --git a/git-submodule.sh b/git-submodule.sh
index 39ebdf2..43eb605 100755
--- a/git-submodule.sh
+++ b/git-submodule.sh
@@ -719,7 +719,7 @@
 # $@ = requested path
 #
 cmd_set_branch() {
-	unset_branch=false
+	default=
 	branch=
 
 	while test $# -ne 0
@@ -729,7 +729,7 @@
 			# we don't do anything with this but we need to accept it
 			;;
 		-d|--default)
-			unset_branch=true
+			default=1
 			;;
 		-b|--branch)
 			case "$2" in '') usage ;; esac
@@ -750,33 +750,7 @@
 		shift
 	done
 
-	if test $# -ne 1
-	then
-		usage
-	fi
-
-	# we can't use `git submodule--helper name` here because internally, it
-	# hashes the path so a trailing slash could lead to an unintentional no match
-	name="$(git submodule--helper list "$1" | cut -f2)"
-	if test -z "$name"
-	then
-		exit 1
-	fi
-
-	test -n "$branch"; has_branch=$?
-	test "$unset_branch" = true; has_unset_branch=$?
-
-	if test $((!$has_branch != !$has_unset_branch)) -eq 0
-	then
-		usage
-	fi
-
-	if test $has_branch -eq 0
-	then
-		git submodule--helper config submodule."$name".branch "$branch"
-	else
-		git submodule--helper config --unset submodule."$name".branch
-	fi
+	git ${wt_prefix:+-C "$wt_prefix"} ${prefix:+--super-prefix "$prefix"} submodule--helper set-branch ${GIT_QUIET:+--quiet} ${branch:+--branch "$branch"} ${default:+--default} -- "$@"
 }
 
 #
diff --git a/http-fetch.c b/http-fetch.c
index a32ac11..1df376e 100644
--- a/http-fetch.c
+++ b/http-fetch.c
@@ -5,59 +5,24 @@
 #include "walker.h"
 
 static const char http_fetch_usage[] = "git http-fetch "
-"[-c] [-t] [-a] [-v] [--recover] [-w ref] [--stdin] commit-id url";
+"[-c] [-t] [-a] [-v] [--recover] [-w ref] [--stdin | --packfile=hash | commit-id] url";
 
-int cmd_main(int argc, const char **argv)
+static int fetch_using_walker(const char *raw_url, int get_verbosely,
+			      int get_recover, int commits, char **commit_id,
+			      const char **write_ref, int commits_on_stdin)
 {
-	struct walker *walker;
-	int commits_on_stdin = 0;
-	int commits;
-	const char **write_ref = NULL;
-	char **commit_id;
 	char *url = NULL;
-	int arg = 1;
-	int rc = 0;
-	int get_verbosely = 0;
-	int get_recover = 0;
+	struct walker *walker;
+	int rc;
 
-	while (arg < argc && argv[arg][0] == '-') {
-		if (argv[arg][1] == 't') {
-		} else if (argv[arg][1] == 'c') {
-		} else if (argv[arg][1] == 'a') {
-		} else if (argv[arg][1] == 'v') {
-			get_verbosely = 1;
-		} else if (argv[arg][1] == 'w') {
-			write_ref = &argv[arg + 1];
-			arg++;
-		} else if (argv[arg][1] == 'h') {
-			usage(http_fetch_usage);
-		} else if (!strcmp(argv[arg], "--recover")) {
-			get_recover = 1;
-		} else if (!strcmp(argv[arg], "--stdin")) {
-			commits_on_stdin = 1;
-		}
-		arg++;
-	}
-	if (argc != arg + 2 - commits_on_stdin)
-		usage(http_fetch_usage);
-	if (commits_on_stdin) {
-		commits = walker_targets_stdin(&commit_id, &write_ref);
-	} else {
-		commit_id = (char **) &argv[arg++];
-		commits = 1;
-	}
-
-	if (argv[arg])
-		str_end_url_with_slash(argv[arg], &url);
-
-	setup_git_directory();
-
-	git_config(git_default_config, NULL);
+	str_end_url_with_slash(raw_url, &url);
 
 	http_init(NULL, url, 0);
+
 	walker = get_http_walker(url);
 	walker->get_verbosely = get_verbosely;
 	walker->get_recover = get_recover;
+	walker->get_progress = 0;
 
 	rc = walker_fetch(walker, commits, commit_id, write_ref, url);
 
@@ -73,8 +38,99 @@
 
 	walker_free(walker);
 	http_cleanup();
-
 	free(url);
 
 	return rc;
 }
+
+static void fetch_single_packfile(struct object_id *packfile_hash,
+				  const char *url) {
+	struct http_pack_request *preq;
+	struct slot_results results;
+	int ret;
+
+	http_init(NULL, url, 0);
+
+	preq = new_direct_http_pack_request(packfile_hash->hash, xstrdup(url));
+	if (preq == NULL)
+		die("couldn't create http pack request");
+	preq->slot->results = &results;
+	preq->generate_keep = 1;
+
+	if (start_active_slot(preq->slot)) {
+		run_active_slot(preq->slot);
+		if (results.curl_result != CURLE_OK) {
+			die("Unable to get pack file %s\n%s", preq->url,
+			    curl_errorstr);
+		}
+	} else {
+		die("Unable to start request");
+	}
+
+	if ((ret = finish_http_pack_request(preq)))
+		die("finish_http_pack_request gave result %d", ret);
+
+	release_http_pack_request(preq);
+	http_cleanup();
+}
+
+int cmd_main(int argc, const char **argv)
+{
+	int commits_on_stdin = 0;
+	int commits;
+	const char **write_ref = NULL;
+	char **commit_id;
+	int arg = 1;
+	int get_verbosely = 0;
+	int get_recover = 0;
+	int packfile = 0;
+	struct object_id packfile_hash;
+
+	while (arg < argc && argv[arg][0] == '-') {
+		const char *p;
+
+		if (argv[arg][1] == 't') {
+		} else if (argv[arg][1] == 'c') {
+		} else if (argv[arg][1] == 'a') {
+		} else if (argv[arg][1] == 'v') {
+			get_verbosely = 1;
+		} else if (argv[arg][1] == 'w') {
+			write_ref = &argv[arg + 1];
+			arg++;
+		} else if (argv[arg][1] == 'h') {
+			usage(http_fetch_usage);
+		} else if (!strcmp(argv[arg], "--recover")) {
+			get_recover = 1;
+		} else if (!strcmp(argv[arg], "--stdin")) {
+			commits_on_stdin = 1;
+		} else if (skip_prefix(argv[arg], "--packfile=", &p)) {
+			const char *end;
+
+			packfile = 1;
+			if (parse_oid_hex(p, &packfile_hash, &end) || *end)
+				die(_("argument to --packfile must be a valid hash (got '%s')"), p);
+		}
+		arg++;
+	}
+	if (argc != arg + 2 - (commits_on_stdin || packfile))
+		usage(http_fetch_usage);
+
+	setup_git_directory();
+
+	git_config(git_default_config, NULL);
+
+	if (packfile) {
+		fetch_single_packfile(&packfile_hash, argv[arg]);
+		return 0;
+	}
+
+	if (commits_on_stdin) {
+		commits = walker_targets_stdin(&commit_id, &write_ref);
+	} else {
+		commit_id = (char **) &argv[arg++];
+		commits = 1;
+	}
+	return fetch_using_walker(argv[arg], get_verbosely, get_recover,
+				  commits, commit_id, write_ref,
+				  commits_on_stdin);
+}
diff --git a/http-push.c b/http-push.c
index 822f326..ac7868f 100644
--- a/http-push.c
+++ b/http-push.c
@@ -117,6 +117,7 @@
 
 struct transfer_request {
 	struct object *obj;
+	struct packed_git *target;
 	char *url;
 	char *dest;
 	struct remote_lock *lock;
@@ -314,17 +315,18 @@
 		release_request(request);
 		return;
 	}
+	close_pack_index(target);
+	request->target = target;
 
 	fprintf(stderr,	"Fetching pack %s\n",
 		hash_to_hex(target->hash));
 	fprintf(stderr, " which contains %s\n", oid_to_hex(&request->obj->oid));
 
-	preq = new_http_pack_request(target, repo->url);
+	preq = new_http_pack_request(target->hash, repo->url);
 	if (preq == NULL) {
 		repo->can_update_info_refs = 0;
 		return;
 	}
-	preq->lst = &repo->packs;
 
 	/* Make sure there isn't another open request for this pack */
 	while (check_request) {
@@ -597,6 +599,8 @@
 		}
 		if (fail)
 			repo->can_update_info_refs = 0;
+		else
+			http_install_packfile(request->target, &repo->packs);
 		release_request(request);
 	}
 }
diff --git a/http-walker.c b/http-walker.c
index fe15e32..4fb1235 100644
--- a/http-walker.c
+++ b/http-walker.c
@@ -439,6 +439,7 @@
 	target = find_sha1_pack(sha1, repo->packs);
 	if (!target)
 		return -1;
+	close_pack_index(target);
 
 	if (walker->get_verbosely) {
 		fprintf(stderr, "Getting pack %s\n",
@@ -447,10 +448,9 @@
 			hash_to_hex(sha1));
 	}
 
-	preq = new_http_pack_request(target, repo->base);
+	preq = new_http_pack_request(target->hash, repo->base);
 	if (preq == NULL)
 		goto abort;
-	preq->lst = &repo->packs;
 	preq->slot->results = &results;
 
 	if (start_active_slot(preq->slot)) {
@@ -469,6 +469,7 @@
 	release_http_pack_request(preq);
 	if (ret)
 		return ret;
+	http_install_packfile(target, &repo->packs);
 
 	return 0;
 
diff --git a/http.c b/http.c
index 4882c9f..3b12843 100644
--- a/http.c
+++ b/http.c
@@ -18,7 +18,7 @@
 
 static struct trace_key trace_curl = TRACE_KEY_INIT(CURL);
 static int trace_curl_data = 1;
-static struct string_list cookies_to_redact = STRING_LIST_INIT_DUP;
+static int trace_curl_redact = 1;
 #if LIBCURL_VERSION_NUM >= 0x070a08
 long int git_curl_ipresolve = CURL_IPRESOLVE_WHATEVER;
 #else
@@ -642,8 +642,9 @@
 {
 	const char *sensitive_header;
 
-	if (skip_prefix(header->buf, "Authorization:", &sensitive_header) ||
-	    skip_prefix(header->buf, "Proxy-Authorization:", &sensitive_header)) {
+	if (trace_curl_redact &&
+	    (skip_prefix(header->buf, "Authorization:", &sensitive_header) ||
+	     skip_prefix(header->buf, "Proxy-Authorization:", &sensitive_header))) {
 		/* The first token is the type, which is OK to log */
 		while (isspace(*sensitive_header))
 			sensitive_header++;
@@ -652,20 +653,15 @@
 		/* Everything else is opaque and possibly sensitive */
 		strbuf_setlen(header,  sensitive_header - header->buf);
 		strbuf_addstr(header, " <redacted>");
-	} else if (cookies_to_redact.nr &&
+	} else if (trace_curl_redact &&
 		   skip_prefix(header->buf, "Cookie:", &sensitive_header)) {
 		struct strbuf redacted_header = STRBUF_INIT;
-		char *cookie;
+		const char *cookie;
 
 		while (isspace(*sensitive_header))
 			sensitive_header++;
 
-		/*
-		 * The contents of header starting from sensitive_header will
-		 * subsequently be overridden, so it is fine to mutate this
-		 * string (hence the assignment to "char *").
-		 */
-		cookie = (char *) sensitive_header;
+		cookie = sensitive_header;
 
 		while (cookie) {
 			char *equals;
@@ -678,14 +674,8 @@
 				strbuf_addstr(&redacted_header, cookie);
 				continue;
 			}
-			*equals = 0; /* temporarily set to NUL for lookup */
-			if (string_list_lookup(&cookies_to_redact, cookie)) {
-				strbuf_addstr(&redacted_header, cookie);
-				strbuf_addstr(&redacted_header, "=<redacted>");
-			} else {
-				*equals = '=';
-				strbuf_addstr(&redacted_header, cookie);
-			}
+			strbuf_add(&redacted_header, cookie, equals - cookie);
+			strbuf_addstr(&redacted_header, "=<redacted>");
 			if (semicolon) {
 				/*
 				 * There are more cookies. (Or, for some
@@ -1003,11 +993,8 @@
 	setup_curl_trace(result);
 	if (getenv("GIT_TRACE_CURL_NO_DATA"))
 		trace_curl_data = 0;
-	if (getenv("GIT_REDACT_COOKIES")) {
-		string_list_split(&cookies_to_redact,
-				  getenv("GIT_REDACT_COOKIES"), ',', -1);
-		string_list_sort(&cookies_to_redact);
-	}
+	if (!git_env_bool("GIT_TRACE_REDACT", 1))
+		trace_curl_redact = 0;
 
 	curl_easy_setopt(result, CURLOPT_USERAGENT,
 		user_agent ? user_agent : git_user_agent());
@@ -2274,70 +2261,74 @@
 
 int finish_http_pack_request(struct http_pack_request *preq)
 {
-	struct packed_git **lst;
-	struct packed_git *p = preq->target;
-	char *tmp_idx;
-	size_t len;
 	struct child_process ip = CHILD_PROCESS_INIT;
-
-	close_pack_index(p);
+	int tmpfile_fd;
+	int ret = 0;
 
 	fclose(preq->packfile);
 	preq->packfile = NULL;
 
-	lst = preq->lst;
+	tmpfile_fd = xopen(preq->tmpfile.buf, O_RDONLY);
+
+	argv_array_push(&ip.args, "index-pack");
+	argv_array_push(&ip.args, "--stdin");
+	ip.git_cmd = 1;
+	ip.in = tmpfile_fd;
+	if (preq->generate_keep) {
+		argv_array_pushf(&ip.args, "--keep=git %"PRIuMAX,
+				 (uintmax_t)getpid());
+		ip.out = 0;
+	} else {
+		ip.no_stdout = 1;
+	}
+
+	if (run_command(&ip)) {
+		ret = -1;
+		goto cleanup;
+	}
+
+cleanup:
+	close(tmpfile_fd);
+	unlink(preq->tmpfile.buf);
+	return ret;
+}
+
+void http_install_packfile(struct packed_git *p,
+			   struct packed_git **list_to_remove_from)
+{
+	struct packed_git **lst = list_to_remove_from;
+
 	while (*lst != p)
 		lst = &((*lst)->next);
 	*lst = (*lst)->next;
 
-	if (!strip_suffix(preq->tmpfile.buf, ".pack.temp", &len))
-		BUG("pack tmpfile does not end in .pack.temp?");
-	tmp_idx = xstrfmt("%.*s.idx.temp", (int)len, preq->tmpfile.buf);
-
-	argv_array_push(&ip.args, "index-pack");
-	argv_array_pushl(&ip.args, "-o", tmp_idx, NULL);
-	argv_array_push(&ip.args, preq->tmpfile.buf);
-	ip.git_cmd = 1;
-	ip.no_stdin = 1;
-	ip.no_stdout = 1;
-
-	if (run_command(&ip)) {
-		unlink(preq->tmpfile.buf);
-		unlink(tmp_idx);
-		free(tmp_idx);
-		return -1;
-	}
-
-	unlink(sha1_pack_index_name(p->hash));
-
-	if (finalize_object_file(preq->tmpfile.buf, sha1_pack_name(p->hash))
-	 || finalize_object_file(tmp_idx, sha1_pack_index_name(p->hash))) {
-		free(tmp_idx);
-		return -1;
-	}
-
 	install_packed_git(the_repository, p);
-	free(tmp_idx);
-	return 0;
 }
 
 struct http_pack_request *new_http_pack_request(
-	struct packed_git *target, const char *base_url)
+	const unsigned char *packed_git_hash, const char *base_url) {
+
+	struct strbuf buf = STRBUF_INIT;
+
+	end_url_with_slash(&buf, base_url);
+	strbuf_addf(&buf, "objects/pack/pack-%s.pack",
+		hash_to_hex(packed_git_hash));
+	return new_direct_http_pack_request(packed_git_hash,
+					    strbuf_detach(&buf, NULL));
+}
+
+struct http_pack_request *new_direct_http_pack_request(
+	const unsigned char *packed_git_hash, char *url)
 {
 	off_t prev_posn = 0;
-	struct strbuf buf = STRBUF_INIT;
 	struct http_pack_request *preq;
 
 	preq = xcalloc(1, sizeof(*preq));
 	strbuf_init(&preq->tmpfile, 0);
-	preq->target = target;
 
-	end_url_with_slash(&buf, base_url);
-	strbuf_addf(&buf, "objects/pack/pack-%s.pack",
-		hash_to_hex(target->hash));
-	preq->url = strbuf_detach(&buf, NULL);
+	preq->url = url;
 
-	strbuf_addf(&preq->tmpfile, "%s.temp", sha1_pack_name(target->hash));
+	strbuf_addf(&preq->tmpfile, "%s.temp", sha1_pack_name(packed_git_hash));
 	preq->packfile = fopen(preq->tmpfile.buf, "a");
 	if (!preq->packfile) {
 		error("Unable to open local file %s for pack",
@@ -2361,7 +2352,7 @@
 		if (http_is_verbose)
 			fprintf(stderr,
 				"Resuming fetch of pack %s at byte %"PRIuMAX"\n",
-				hash_to_hex(target->hash),
+				hash_to_hex(packed_git_hash),
 				(uintmax_t)prev_posn);
 		http_opt_request_remainder(preq->slot->curl, prev_posn);
 	}
diff --git a/http.h b/http.h
index faf8cbb..5de792e 100644
--- a/http.h
+++ b/http.h
@@ -216,18 +216,36 @@
 
 struct http_pack_request {
 	char *url;
-	struct packed_git *target;
-	struct packed_git **lst;
+
+	/*
+	 * If this is true, finish_http_pack_request() will pass "--keep" to
+	 * index-pack, resulting in the creation of a keep file, and will not
+	 * suppress its stdout (that is, the "keep\t<hash>\n" line will be
+	 * printed to stdout).
+	 */
+	unsigned generate_keep : 1;
+
 	FILE *packfile;
 	struct strbuf tmpfile;
 	struct active_request_slot *slot;
 };
 
 struct http_pack_request *new_http_pack_request(
-	struct packed_git *target, const char *base_url);
+	const unsigned char *packed_git_hash, const char *base_url);
+struct http_pack_request *new_direct_http_pack_request(
+	const unsigned char *packed_git_hash, char *url);
 int finish_http_pack_request(struct http_pack_request *preq);
 void release_http_pack_request(struct http_pack_request *preq);
 
+/*
+ * Remove p from the given list, and invoke install_packed_git() on it.
+ *
+ * This is a convenience function for users that have obtained a list of packs
+ * from http_get_info_packs() and have chosen a specific pack to fetch.
+ */
+void http_install_packfile(struct packed_git *p,
+			   struct packed_git **list_to_remove_from);
+
 /* Helpers for fetching object */
 struct http_object_request {
 	char *url;
diff --git a/list-objects-filter-options.c b/list-objects-filter-options.c
index 256bcfb..3553ad7 100644
--- a/list-objects-filter-options.c
+++ b/list-objects-filter-options.c
@@ -326,7 +326,8 @@
 
 	/* Check if it is already registered */
 	if (!promisor_remote_find(remote)) {
-		git_config_set("core.repositoryformatversion", "1");
+		if (upgrade_repository_format(1) < 0)
+			die(_("unable to upgrade repository format to support partial clone"));
 
 		/* Add promisor config for the remote */
 		cfg_name = xstrfmt("remote.%s.promisor", remote);
diff --git a/repository.h b/repository.h
index 6534fbb..3c1f7d5 100644
--- a/repository.h
+++ b/repository.h
@@ -196,4 +196,10 @@
 
 void prepare_repo_settings(struct repository *r);
 
+/*
+ * Return 1 if upgrade repository format to target_version succeeded,
+ * 0 if no upgrade is necessary, and -1 when upgrade is not possible.
+ */
+int upgrade_repository_format(int target_version);
+
 #endif /* REPOSITORY_H */
diff --git a/setup.c b/setup.c
index 65fe5ec..eb066db 100644
--- a/setup.c
+++ b/setup.c
@@ -455,6 +455,7 @@
 	if (strcmp(var, "core.repositoryformatversion") == 0)
 		data->version = git_config_int(var, value);
 	else if (skip_prefix(var, "extensions.", &ext)) {
+		data->has_extensions = 1;
 		/*
 		 * record any known extensions here; otherwise,
 		 * we fall through to recording it as unknown, and
@@ -506,9 +507,15 @@
 		die("%s", err.buf);
 	}
 
-	repository_format_precious_objects = candidate->precious_objects;
-	set_repository_format_partial_clone(candidate->partial_clone);
-	repository_format_worktree_config = candidate->worktree_config;
+	if (candidate->version >= 1) {
+		repository_format_precious_objects = candidate->precious_objects;
+		set_repository_format_partial_clone(candidate->partial_clone);
+		repository_format_worktree_config = candidate->worktree_config;
+	} else {
+		repository_format_precious_objects = 0;
+		set_repository_format_partial_clone(NULL);
+		repository_format_worktree_config = 0;
+	}
 	string_list_clear(&candidate->unknown_extensions, 0);
 
 	if (repository_format_worktree_config) {
@@ -538,6 +545,34 @@
 	return 0;
 }
 
+int upgrade_repository_format(int target_version)
+{
+	struct strbuf sb = STRBUF_INIT;
+	struct strbuf err = STRBUF_INIT;
+	struct strbuf repo_version = STRBUF_INIT;
+	struct repository_format repo_fmt = REPOSITORY_FORMAT_INIT;
+
+	strbuf_git_common_path(&sb, the_repository, "config");
+	read_repository_format(&repo_fmt, sb.buf);
+	strbuf_release(&sb);
+
+	if (repo_fmt.version >= target_version)
+		return 0;
+
+	if (verify_repository_format(&repo_fmt, &err) < 0 ||
+	    (!repo_fmt.version && repo_fmt.has_extensions)) {
+		warning("unable to upgrade repository format from %d to %d: %s",
+			repo_fmt.version, target_version, err.buf);
+		strbuf_release(&err);
+		return -1;
+	}
+
+	strbuf_addf(&repo_version, "%d", target_version);
+	git_config_set("core.repositoryformatversion", repo_version.buf);
+	strbuf_release(&repo_version);
+	return 1;
+}
+
 static void init_repository_format(struct repository_format *format)
 {
 	const struct repository_format fresh = REPOSITORY_FORMAT_INIT;
diff --git a/strbuf.c b/strbuf.c
index 2f1a7d3..e3397cc 100644
--- a/strbuf.c
+++ b/strbuf.c
@@ -556,11 +556,6 @@
 	return sb->len ? fwrite(sb->buf, 1, sb->len, f) : 0;
 }
 
-ssize_t strbuf_write_fd(struct strbuf *sb, int fd)
-{
-	return sb->len ? write(fd, sb->buf, sb->len) : 0;
-}
-
 #define STRBUF_MAXLINK (2*PATH_MAX)
 
 int strbuf_readlink(struct strbuf *sb, const char *path, size_t hint)
diff --git a/strbuf.h b/strbuf.h
index 7062eb6..223ee20 100644
--- a/strbuf.h
+++ b/strbuf.h
@@ -473,7 +473,6 @@
  * NUL bytes.
  */
 ssize_t strbuf_write(struct strbuf *sb, FILE *stream);
-ssize_t strbuf_write_fd(struct strbuf *sb, int fd);
 
 /**
  * Read a line from a FILE *, overwriting the existing contents of
diff --git a/t/t0410-partial-clone.sh b/t/t0410-partial-clone.sh
index a3988bd..463dc3a 100755
--- a/t/t0410-partial-clone.sh
+++ b/t/t0410-partial-clone.sh
@@ -30,6 +30,29 @@
 	git -C client fetch origin
 '
 
+test_expect_success 'convert shallow clone to partial clone' '
+	rm -fr server client &&
+	test_create_repo server &&
+	test_commit -C server my_commit 1 &&
+	test_commit -C server my_commit2 1 &&
+	git clone --depth=1 "file://$(pwd)/server" client &&
+	git -C client fetch --unshallow --filter="blob:none" &&
+	test_cmp_config -C client true remote.origin.promisor &&
+	test_cmp_config -C client blob:none remote.origin.partialclonefilter &&
+	test_cmp_config -C client 1 core.repositoryformatversion
+'
+
+test_expect_success 'convert shallow clone to partial clone must fail with any extension' '
+	rm -fr server client &&
+	test_create_repo server &&
+	test_commit -C server my_commit 1 &&
+	test_commit -C server my_commit2 1 &&
+	git clone --depth=1 "file://$(pwd)/server" client &&
+	test_cmp_config -C client 0 core.repositoryformatversion &&
+	git -C client config extensions.partialclone origin &&
+	test_must_fail git -C client fetch --unshallow --filter="blob:none"
+'
+
 test_expect_success 'missing reflog object, but promised by a commit, passes fsck' '
 	rm -rf repo &&
 	test_create_repo repo &&
diff --git a/t/t1090-sparse-checkout-scope.sh b/t/t1090-sparse-checkout-scope.sh
index 40cc004..f35a73d 100755
--- a/t/t1090-sparse-checkout-scope.sh
+++ b/t/t1090-sparse-checkout-scope.sh
@@ -63,7 +63,6 @@
 	git -C server commit -m message &&
 
 	test_config -C client core.sparsecheckout 1 &&
-	test_config -C client extensions.partialclone origin &&
 	echo "!/*" >client/.git/info/sparse-checkout &&
 	echo "/a" >>client/.git/info/sparse-checkout &&
 	git -C client fetch --filter=blob:none origin &&
diff --git a/t/t2401-worktree-prune.sh b/t/t2401-worktree-prune.sh
index b7d6d5d..a6ce7f5 100755
--- a/t/t2401-worktree-prune.sh
+++ b/t/t2401-worktree-prune.sh
@@ -92,4 +92,28 @@
 	test -d .git/worktrees/nop
 '
 
+test_expect_success 'prune duplicate (linked/linked)' '
+	test_when_finished rm -fr .git/worktrees w1 w2 &&
+	git worktree add --detach w1 &&
+	git worktree add --detach w2 &&
+	sed "s/w2/w1/" .git/worktrees/w2/gitdir >.git/worktrees/w2/gitdir.new &&
+	mv .git/worktrees/w2/gitdir.new .git/worktrees/w2/gitdir &&
+	git worktree prune --verbose >actual &&
+	test_i18ngrep "duplicate entry" actual &&
+	test -d .git/worktrees/w1 &&
+	! test -d .git/worktrees/w2
+'
+
+test_expect_success 'prune duplicate (main/linked)' '
+	test_when_finished rm -fr repo wt &&
+	test_create_repo repo &&
+	test_commit -C repo x &&
+	git -C repo worktree add --detach ../wt &&
+	rm -fr wt &&
+	mv repo wt &&
+	git -C wt worktree prune --verbose >actual &&
+	test_i18ngrep "duplicate entry" actual &&
+	! test -d .git/worktrees/wt
+'
+
 test_done
diff --git a/t/t2403-worktree-move.sh b/t/t2403-worktree-move.sh
index 939d18d..a4e1a17 100755
--- a/t/t2403-worktree-move.sh
+++ b/t/t2403-worktree-move.sh
@@ -112,6 +112,27 @@
 	git worktree move --force --force flump ploof
 '
 
+test_expect_success 'refuse to move worktree atop existing path' '
+	>bobble &&
+	git worktree add --detach beeble &&
+	test_must_fail git worktree move beeble bobble
+'
+
+test_expect_success 'move atop existing but missing worktree' '
+	git worktree add --detach gnoo &&
+	git worktree add --detach pneu &&
+	rm -fr pneu &&
+	test_must_fail git worktree move gnoo pneu &&
+	git worktree move --force gnoo pneu &&
+
+	git worktree add --detach nu &&
+	git worktree lock nu &&
+	rm -fr nu &&
+	test_must_fail git worktree move pneu nu &&
+	test_must_fail git worktree --force move pneu nu &&
+	git worktree move --force --force pneu nu
+'
+
 test_expect_success 'move a repo with uninitialized submodule' '
 	git init withsub &&
 	(
diff --git a/t/t2404-worktree-config.sh b/t/t2404-worktree-config.sh
index 286121d..9536d10 100755
--- a/t/t2404-worktree-config.sh
+++ b/t/t2404-worktree-config.sh
@@ -23,8 +23,10 @@
 '
 
 test_expect_success 'enable worktreeConfig extension' '
+	git config core.repositoryformatversion 1 &&
 	git config extensions.worktreeConfig true &&
-	test_cmp_config true extensions.worktreeConfig
+	test_cmp_config true extensions.worktreeConfig &&
+	test_cmp_config 1 core.repositoryformatversion
 '
 
 test_expect_success 'config is shared as before' '
diff --git a/t/t3200-branch.sh b/t/t3200-branch.sh
index 411a70b..1fd03ca 100755
--- a/t/t3200-branch.sh
+++ b/t/t3200-branch.sh
@@ -323,11 +323,11 @@
 
 test_expect_success 'git branch --column' '
 	COLUMNS=81 git branch --column=column >actual &&
-	cat >expected <<\EOF &&
+	cat >expect <<\EOF &&
   a/b/c     bam       foo       l       * master    mb        o/o       q
   abc       bar       j/k       m/m       master2   n         o/p       r
 EOF
-	test_cmp expected actual
+	test_cmp expect actual
 '
 
 test_expect_success 'git branch --column with an extremely long branch name' '
@@ -336,7 +336,7 @@
 	test_when_finished "git branch -d $long" &&
 	git branch $long &&
 	COLUMNS=80 git branch --column=column >actual &&
-	cat >expected <<EOF &&
+	cat >expect <<EOF &&
   a/b/c
   abc
   bam
@@ -355,7 +355,7 @@
   r
   $long
 EOF
-	test_cmp expected actual
+	test_cmp expect actual
 '
 
 test_expect_success 'git branch with column.*' '
@@ -364,11 +364,11 @@
 	COLUMNS=80 git branch >actual &&
 	git config --unset column.branch &&
 	git config --unset column.ui &&
-	cat >expected <<\EOF &&
+	cat >expect <<\EOF &&
   a/b/c   bam   foo   l   * master    mb   o/o   q
   abc     bar   j/k   m/m   master2   n    o/p   r
 EOF
-	test_cmp expected actual
+	test_cmp expect actual
 '
 
 test_expect_success 'git branch --column -v should fail' '
@@ -379,7 +379,7 @@
 	git config column.ui column &&
 	COLUMNS=80 git branch -v | cut -c -10 | sed "s/ *$//" >actual &&
 	git config --unset column.ui &&
-	cat >expected <<\EOF &&
+	cat >expect <<\EOF &&
   a/b/c
   abc
   bam
@@ -397,7 +397,7 @@
   q
   r
 EOF
-	test_cmp expected actual
+	test_cmp expect actual
 '
 
 mv .git/config .git/config-saved
@@ -835,32 +835,42 @@
 '
 
 test_expect_success '--set-upstream-to fails on multiple branches' '
-	test_must_fail git branch --set-upstream-to master a b c
+	echo "fatal: too many arguments to set new upstream" >expect &&
+	test_must_fail git branch --set-upstream-to master a b c 2>err &&
+	test_i18ncmp expect err
 '
 
 test_expect_success '--set-upstream-to fails on detached HEAD' '
 	git checkout HEAD^{} &&
-	test_must_fail git branch --set-upstream-to master &&
-	git checkout -
+	test_when_finished git checkout - &&
+	echo "fatal: could not set upstream of HEAD to master when it does not point to any branch." >expect &&
+	test_must_fail git branch --set-upstream-to master 2>err &&
+	test_i18ncmp expect err
 '
 
 test_expect_success '--set-upstream-to fails on a missing dst branch' '
-	test_must_fail git branch --set-upstream-to master does-not-exist
+	echo "fatal: branch '"'"'does-not-exist'"'"' does not exist" >expect &&
+	test_must_fail git branch --set-upstream-to master does-not-exist 2>err &&
+	test_i18ncmp expect err
 '
 
 test_expect_success '--set-upstream-to fails on a missing src branch' '
-	test_must_fail git branch --set-upstream-to does-not-exist master
+	test_must_fail git branch --set-upstream-to does-not-exist master 2>err &&
+	test_i18ngrep "the requested upstream branch '"'"'does-not-exist'"'"' does not exist" err
 '
 
 test_expect_success '--set-upstream-to fails on a non-ref' '
-	test_must_fail git branch --set-upstream-to HEAD^{}
+	echo "fatal: Cannot setup tracking information; starting point '"'"'HEAD^{}'"'"' is not a branch." >expect &&
+	test_must_fail git branch --set-upstream-to HEAD^{} 2>err &&
+	test_i18ncmp expect err
 '
 
 test_expect_success '--set-upstream-to fails on locked config' '
 	test_when_finished "rm -f .git/config.lock" &&
 	>.git/config.lock &&
 	git branch locked &&
-	test_must_fail git branch --set-upstream-to locked
+	test_must_fail git branch --set-upstream-to locked 2>err &&
+	test_i18ngrep "could not lock config file .git/config: File exists" err
 '
 
 test_expect_success 'use --set-upstream-to modify HEAD' '
@@ -881,14 +891,17 @@
 '
 
 test_expect_success '--unset-upstream should fail if given a non-existent branch' '
-	test_must_fail git branch --unset-upstream i-dont-exist
+	echo "fatal: Branch '"'"'i-dont-exist'"'"' has no upstream information" >expect &&
+	test_must_fail git branch --unset-upstream i-dont-exist 2>err &&
+	test_i18ncmp expect err
 '
 
 test_expect_success '--unset-upstream should fail if config is locked' '
 	test_when_finished "rm -f .git/config.lock" &&
 	git branch --set-upstream-to locked &&
 	>.git/config.lock &&
-	test_must_fail git branch --unset-upstream
+	test_must_fail git branch --unset-upstream 2>err &&
+	test_i18ngrep "could not lock config file .git/config: File exists" err
 '
 
 test_expect_success 'test --unset-upstream on HEAD' '
@@ -900,17 +913,23 @@
 	test_must_fail git config branch.master.remote &&
 	test_must_fail git config branch.master.merge &&
 	# fail for a branch without upstream set
-	test_must_fail git branch --unset-upstream
+	echo "fatal: Branch '"'"'master'"'"' has no upstream information" >expect &&
+	test_must_fail git branch --unset-upstream 2>err &&
+	test_i18ncmp expect err
 '
 
 test_expect_success '--unset-upstream should fail on multiple branches' '
-	test_must_fail git branch --unset-upstream a b c
+	echo "fatal: too many arguments to unset upstream" >expect &&
+	test_must_fail git branch --unset-upstream a b c 2>err &&
+	test_i18ncmp expect err
 '
 
 test_expect_success '--unset-upstream should fail on detached HEAD' '
 	git checkout HEAD^{} &&
-	test_must_fail git branch --unset-upstream &&
-	git checkout -
+	test_when_finished git checkout - &&
+	echo "fatal: could not unset upstream of HEAD when it does not point to any branch." >expect &&
+	test_must_fail git branch --unset-upstream 2>err &&
+	test_i18ncmp expect err
 '
 
 test_expect_success 'test --unset-upstream on a particular branch' '
@@ -922,17 +941,17 @@
 '
 
 test_expect_success 'disabled option --set-upstream fails' '
-    test_must_fail git branch --set-upstream origin/master
+	test_must_fail git branch --set-upstream origin/master
 '
 
 test_expect_success '--set-upstream-to notices an error to set branch as own upstream' '
 	git branch --set-upstream-to refs/heads/my13 my13 2>actual &&
-	cat >expected <<-\EOF &&
+	cat >expect <<-\EOF &&
 	warning: Not setting branch my13 as its own upstream.
 	EOF
 	test_expect_code 1 git config branch.my13.remote &&
 	test_expect_code 1 git config branch.my13.merge &&
-	test_i18ncmp expected actual
+	test_i18ncmp expect actual
 '
 
 # Keep this test last, as it changes the current branch
diff --git a/t/t3430-rebase-merges.sh b/t/t3430-rebase-merges.sh
index a1bc3e2..b454f40 100755
--- a/t/t3430-rebase-merges.sh
+++ b/t/t3430-rebase-merges.sh
@@ -420,7 +420,7 @@
 	git commit --fixup B B.t &&
 	write_script show.sh <<-\EOF &&
 	subject="$(git show -s --format=%s HEAD)"
-	content="$(git diff HEAD^! | tail -n 1)"
+	content="$(git diff HEAD^ HEAD | tail -n 1)"
 	echo "$subject: $content"
 	EOF
 	test_tick &&
diff --git a/t/t4014-format-patch.sh b/t/t4014-format-patch.sh
index 575e079..958c2da 100755
--- a/t/t4014-format-patch.sh
+++ b/t/t4014-format-patch.sh
@@ -81,16 +81,16 @@
 '
 
 test_expect_success "format-patch doesn't consider merge commits" '
-	git checkout -b slave master &&
+	git checkout -b feature master &&
 	echo "Another line" >>file &&
 	test_tick &&
-	git commit -am "Slave change #1" &&
+	git commit -am "Feature branch change #1" &&
 	echo "Yet another line" >>file &&
 	test_tick &&
-	git commit -am "Slave change #2" &&
+	git commit -am "Feature branch change #2" &&
 	git checkout -b merger master &&
 	test_tick &&
-	git merge --no-ff slave &&
+	git merge --no-ff feature &&
 	git format-patch -3 --stdout >patch &&
 	grep "^From " patch >from &&
 	test_line_count = 3 from
diff --git a/t/t4068-diff-symmetric.sh b/t/t4068-diff-symmetric.sh
new file mode 100755
index 0000000..31d17a5
--- /dev/null
+++ b/t/t4068-diff-symmetric.sh
@@ -0,0 +1,91 @@
+#!/bin/sh
+
+test_description='behavior of diff with symmetric-diff setups'
+
+. ./test-lib.sh
+
+# build these situations:
+#  - normal merge with one merge base (br1...b2r);
+#  - criss-cross merge ie 2 merge bases (br1...master);
+#  - disjoint subgraph (orphan branch, br3...master).
+#
+#     B---E   <-- master
+#    / \ /
+#   A   X
+#    \ / \
+#     C---D--G   <-- br1
+#      \    /
+#       ---F   <-- br2
+#
+#  H  <-- br3
+#
+# We put files into a few commits so that we can verify the
+# output as well.
+
+test_expect_success setup '
+	git commit --allow-empty -m A &&
+	echo b >b &&
+	git add b &&
+	git commit -m B &&
+	git checkout -b br1 HEAD^ &&
+	echo c >c &&
+	git add c &&
+	git commit -m C &&
+	git tag commit-C &&
+	git merge -m D master &&
+	git tag commit-D &&
+	git checkout master &&
+	git merge -m E commit-C &&
+	git checkout -b br2 commit-C &&
+	echo f >f &&
+	git add f &&
+	git commit -m F &&
+	git checkout br1 &&
+	git merge -m G br2 &&
+	git checkout --orphan br3 &&
+	git commit -m H
+'
+
+test_expect_success 'diff with one merge base' '
+	git diff commit-D...br1 >tmp &&
+	tail -n 1 tmp >actual &&
+	echo +f >expect &&
+	test_cmp expect actual
+'
+
+# The output (in tmp) can have +b or +c depending
+# on which merge base (commit B or C) is picked.
+# It should have one of those two, which comes out
+# to seven lines.
+test_expect_success 'diff with two merge bases' '
+	git diff br1...master >tmp 2>err &&
+	test_line_count = 7 tmp &&
+	test_line_count = 1 err
+'
+
+test_expect_success 'diff with no merge bases' '
+	test_must_fail git diff br2...br3 >tmp 2>err &&
+	test_i18ngrep "fatal: br2...br3: no merge base" err
+'
+
+test_expect_success 'diff with too many symmetric differences' '
+	test_must_fail git diff br1...master br2...br3 >tmp 2>err &&
+	test_i18ngrep "usage" err
+'
+
+test_expect_success 'diff with symmetric difference and extraneous arg' '
+	test_must_fail git diff master br1...master >tmp 2>err &&
+	test_i18ngrep "usage" err
+'
+
+test_expect_success 'diff with two ranges' '
+	test_must_fail git diff master br1..master br2..br3 >tmp 2>err &&
+	test_i18ngrep "usage" err
+'
+
+test_expect_success 'diff with ranges and extra arg' '
+	test_must_fail git diff master br1..master commit-D >tmp 2>err &&
+	test_i18ngrep "usage" err
+'
+
+test_done
diff --git a/t/t5500-fetch-pack.sh b/t/t5500-fetch-pack.sh
index 8c54e34..0f5ff25 100755
--- a/t/t5500-fetch-pack.sh
+++ b/t/t5500-fetch-pack.sh
@@ -999,7 +999,6 @@
 	test_config -C "$SERVER" uploadpack.allowfilter 1 &&
 
 	git clone "$URL" client &&
-	test_config -C client extensions.partialclone origin &&
 
 	test_commit -C "$SERVER" two &&
 
diff --git a/t/t5550-http-fetch-dumb.sh b/t/t5550-http-fetch-dumb.sh
index 5048530..ca2e8af 100755
--- a/t/t5550-http-fetch-dumb.sh
+++ b/t/t5550-http-fetch-dumb.sh
@@ -199,6 +199,28 @@
 	git clone $HTTPD_URL/dumb/repo_pack.git
 '
 
+test_expect_success 'http-fetch --packfile' '
+	# Arbitrary hash. Use rev-parse so that we get one of the correct
+	# length.
+	ARBITRARY=$(git -C "$HTTPD_DOCUMENT_ROOT_PATH"/repo_pack.git rev-parse HEAD) &&
+
+	git init packfileclient &&
+	p=$(cd "$HTTPD_DOCUMENT_ROOT_PATH"/repo_pack.git && ls objects/pack/pack-*.pack) &&
+	git -C packfileclient http-fetch --packfile=$ARBITRARY "$HTTPD_URL"/dumb/repo_pack.git/$p >out &&
+
+	grep "^keep.[0-9a-f]\{16,\}$" out &&
+	cut -c6- out >packhash &&
+
+	# Ensure that the expected files are generated
+	test -e "packfileclient/.git/objects/pack/pack-$(cat packhash).pack" &&
+	test -e "packfileclient/.git/objects/pack/pack-$(cat packhash).idx" &&
+	test -e "packfileclient/.git/objects/pack/pack-$(cat packhash).keep" &&
+
+	# Ensure that it has the HEAD of repo_pack, at least
+	HASH=$(git -C "$HTTPD_DOCUMENT_ROOT_PATH"/repo_pack.git rev-parse HEAD) &&
+	git -C packfileclient cat-file -e "$HASH"
+'
+
 test_expect_success 'fetch notices corrupt pack' '
 	cp -R "$HTTPD_DOCUMENT_ROOT_PATH"/repo_pack.git "$HTTPD_DOCUMENT_ROOT_PATH"/repo_bad1.git &&
 	(cd "$HTTPD_DOCUMENT_ROOT_PATH"/repo_bad1.git &&
@@ -214,6 +236,14 @@
 	)
 '
 
+test_expect_success 'http-fetch --packfile with corrupt pack' '
+	rm -rf packfileclient &&
+	git init packfileclient &&
+	p=$(cd "$HTTPD_DOCUMENT_ROOT_PATH"/repo_bad1.git && ls objects/pack/pack-*.pack) &&
+	test_must_fail git -C packfileclient http-fetch --packfile \
+		"$HTTPD_URL"/dumb/repo_bad1.git/$p
+'
+
 test_expect_success 'fetch notices corrupt idx' '
 	cp -R "$HTTPD_DOCUMENT_ROOT_PATH"/repo_pack.git "$HTTPD_DOCUMENT_ROOT_PATH"/repo_bad2.git &&
 	(cd "$HTTPD_DOCUMENT_ROOT_PATH"/repo_bad2.git &&
diff --git a/t/t5551-http-fetch-smart.sh b/t/t5551-http-fetch-smart.sh
index be01cf7..e40e9ed 100755
--- a/t/t5551-http-fetch-smart.sh
+++ b/t/t5551-http-fetch-smart.sh
@@ -209,6 +209,16 @@
 	grep "Authorization: Basic <redacted>" trace
 '
 
+test_expect_success 'GIT_TRACE_CURL does not redact auth details if GIT_TRACE_REDACT=0' '
+	rm -rf redact-auth trace &&
+	set_askpass user@host pass@host &&
+	GIT_TRACE_REDACT=0 GIT_TRACE_CURL="$(pwd)/trace" \
+		git clone --bare "$HTTPD_URL/auth/smart/repo.git" redact-auth &&
+	expect_askpass both user@host &&
+
+	grep "Authorization: Basic [0-9a-zA-Z+/]" trace
+'
+
 test_expect_success 'disable dumb http on server' '
 	git --git-dir="$HTTPD_DOCUMENT_ROOT_PATH/repo.git" \
 		config http.getanyfile false
@@ -454,39 +464,39 @@
 		--no-tags origin $(cat bar_hash)
 '
 
-test_expect_success 'GIT_REDACT_COOKIES redacts cookies' '
+test_expect_success 'cookies are redacted by default' '
 	rm -rf clone &&
 	echo "Set-Cookie: Foo=1" >cookies &&
 	echo "Set-Cookie: Bar=2" >>cookies &&
-	GIT_TRACE_CURL=true GIT_REDACT_COOKIES=Bar,Baz \
+	GIT_TRACE_CURL=true \
 		git -c "http.cookieFile=$(pwd)/cookies" clone \
 		$HTTPD_URL/smart/repo.git clone 2>err &&
-	grep "Cookie:.*Foo=1" err &&
+	grep "Cookie:.*Foo=<redacted>" err &&
 	grep "Cookie:.*Bar=<redacted>" err &&
+	! grep "Cookie:.*Foo=1" err &&
 	! grep "Cookie:.*Bar=2" err
 '
 
-test_expect_success 'GIT_REDACT_COOKIES redacts cookies when GIT_CURL_VERBOSE=1' '
-	rm -rf clone &&
-	echo "Set-Cookie: Foo=1" >cookies &&
-	echo "Set-Cookie: Bar=2" >>cookies &&
-	GIT_CURL_VERBOSE=1 GIT_REDACT_COOKIES=Bar,Baz \
-		git -c "http.cookieFile=$(pwd)/cookies" clone \
-		$HTTPD_URL/smart/repo.git clone 2>err &&
-	grep "Cookie:.*Foo=1" err &&
-	grep "Cookie:.*Bar=<redacted>" err &&
-	! grep "Cookie:.*Bar=2" err
-'
-
-test_expect_success 'GIT_REDACT_COOKIES handles empty values' '
+test_expect_success 'empty values of cookies are also redacted' '
 	rm -rf clone &&
 	echo "Set-Cookie: Foo=" >cookies &&
-	GIT_TRACE_CURL=true GIT_REDACT_COOKIES=Foo \
+	GIT_TRACE_CURL=true \
 		git -c "http.cookieFile=$(pwd)/cookies" clone \
 		$HTTPD_URL/smart/repo.git clone 2>err &&
 	grep "Cookie:.*Foo=<redacted>" err
 '
 
+test_expect_success 'GIT_TRACE_REDACT=0 disables cookie redaction' '
+	rm -rf clone &&
+	echo "Set-Cookie: Foo=1" >cookies &&
+	echo "Set-Cookie: Bar=2" >>cookies &&
+	GIT_TRACE_REDACT=0 GIT_TRACE_CURL=true \
+		git -c "http.cookieFile=$(pwd)/cookies" clone \
+		$HTTPD_URL/smart/repo.git clone 2>err &&
+	grep "Cookie:.*Foo=1" err &&
+	grep "Cookie:.*Bar=2" err
+'
+
 test_expect_success 'GIT_TRACE_CURL_NO_DATA prevents data from being traced' '
 	rm -rf clone &&
 	GIT_TRACE_CURL=true \
diff --git a/t/t5702-protocol-v2.sh b/t/t5702-protocol-v2.sh
index 8da65e6..baf1d7b 100755
--- a/t/t5702-protocol-v2.sh
+++ b/t/t5702-protocol-v2.sh
@@ -348,7 +348,6 @@
 	rm -rf client "$(pwd)/trace" &&
 	git init client &&
 	SERVER="file://$(pwd)/server" &&
-	test_config -C client extensions.partialClone "$SERVER" &&
 
 	GIT_TRACE_PACKET="$(pwd)/trace" git -C client -c protocol.version=2 \
 		fetch --filter=blob:none "$SERVER" master:refs/heads/other &&
@@ -795,6 +794,94 @@
 	test_i18ngrep "expected no other sections to be sent after no .ready." err
 '
 
+configure_exclusion () {
+	git -C "$1" hash-object "$2" >objh &&
+	git -C "$1" pack-objects "$HTTPD_DOCUMENT_ROOT_PATH/mypack" <objh >packh &&
+	git -C "$1" config --add \
+		"uploadpack.blobpackfileuri" \
+		"$(cat objh) $(cat packh) $HTTPD_URL/dumb/mypack-$(cat packh).pack" &&
+	cat objh
+}
+
+test_expect_success 'part of packfile response provided as URI' '
+	P="$HTTPD_DOCUMENT_ROOT_PATH/http_parent" &&
+	rm -rf "$P" http_child log &&
+
+	git init "$P" &&
+	git -C "$P" config "uploadpack.allowsidebandall" "true" &&
+
+	echo my-blob >"$P/my-blob" &&
+	git -C "$P" add my-blob &&
+	echo other-blob >"$P/other-blob" &&
+	git -C "$P" add other-blob &&
+	git -C "$P" commit -m x &&
+
+	configure_exclusion "$P" my-blob >h &&
+	configure_exclusion "$P" other-blob >h2 &&
+
+	GIT_TRACE=1 GIT_TRACE_PACKET="$(pwd)/log" GIT_TEST_SIDEBAND_ALL=1 \
+	git -c protocol.version=2 \
+		-c fetch.uriprotocols=http,https \
+		clone "$HTTPD_URL/smart/http_parent" http_child &&
+
+	# Ensure that my-blob and other-blob are in separate packfiles.
+	for idx in http_child/.git/objects/pack/*.idx
+	do
+		git verify-pack --verbose $idx >out &&
+		{
+			grep "^[0-9a-f]\{16,\} " out || :
+		} >out.objectlist &&
+		if test_line_count = 1 out.objectlist
+		then
+			if grep $(cat h) out
+			then
+				>hfound
+			fi &&
+			if grep $(cat h2) out
+			then
+				>h2found
+			fi
+		fi
+	done &&
+	test -f hfound &&
+	test -f h2found &&
+
+	# Ensure that there are exactly 6 files (3 .pack and 3 .idx).
+	ls http_child/.git/objects/pack/* >filelist &&
+	test_line_count = 6 filelist
+'
+
+test_expect_success 'fetching with valid packfile URI but invalid hash fails' '
+	P="$HTTPD_DOCUMENT_ROOT_PATH/http_parent" &&
+	rm -rf "$P" http_child log &&
+
+	git init "$P" &&
+	git -C "$P" config "uploadpack.allowsidebandall" "true" &&
+
+	echo my-blob >"$P/my-blob" &&
+	git -C "$P" add my-blob &&
+	echo other-blob >"$P/other-blob" &&
+	git -C "$P" add other-blob &&
+	git -C "$P" commit -m x &&
+
+	configure_exclusion "$P" my-blob >h &&
+	# Configure a URL for other-blob. Just reuse the hash of the object as
+	# the hash of the packfile, since the hash does not matter for this
+	# test as long as it is not the hash of the pack, and it is of the
+	# expected length.
+	git -C "$P" hash-object other-blob >objh &&
+	git -C "$P" pack-objects "$HTTPD_DOCUMENT_ROOT_PATH/mypack" <objh >packh &&
+	git -C "$P" config --add \
+		"uploadpack.blobpackfileuri" \
+		"$(cat objh) $(cat objh) $HTTPD_URL/dumb/mypack-$(cat packh).pack" &&
+
+	test_must_fail env GIT_TEST_SIDEBAND_ALL=1 \
+		git -c protocol.version=2 \
+		-c fetch.uriprotocols=http,https \
+		clone "$HTTPD_URL/smart/http_parent" http_child 2>err &&
+	test_i18ngrep "pack downloaded from.*does not match expected hash" err
+'
+
 # DO NOT add non-httpd-specific tests here, because the last part of this
 # test script is only executed when httpd is available and enabled.
 
diff --git a/t/t9902-completion.sh b/t/t9902-completion.sh
index 3c44af6..8f434a0 100755
--- a/t/t9902-completion.sh
+++ b/t/t9902-completion.sh
@@ -1240,6 +1240,461 @@
 	test_cmp expected out
 '
 
+test_expect_success 'git switch - with no options, complete local branches and unique remote branch names for DWIM logic' '
+	test_completion "git switch " <<-\EOF
+	branch-in-other Z
+	master Z
+	master-in-other Z
+	matching-branch Z
+	EOF
+'
+
+test_expect_success 'git checkout - completes refs and unique remote branches for DWIM' '
+	test_completion "git checkout " <<-\EOF
+	HEAD Z
+	branch-in-other Z
+	master Z
+	master-in-other Z
+	matching-branch Z
+	matching-tag Z
+	other/branch-in-other Z
+	other/master-in-other Z
+	EOF
+'
+
+test_expect_success 'git switch - with --no-guess, complete only local branches' '
+	test_completion "git switch --no-guess " <<-\EOF
+	master Z
+	matching-branch Z
+	EOF
+'
+
+test_expect_success 'git switch - with GIT_COMPLETION_CHECKOUT_NO_GUESS=1, complete only local branches' '
+	GIT_COMPLETION_CHECKOUT_NO_GUESS=1 test_completion "git switch " <<-\EOF
+	master Z
+	matching-branch Z
+	EOF
+'
+
+test_expect_success 'git switch - --guess overrides GIT_COMPLETION_CHECKOUT_NO_GUESS=1, complete local branches and unique remote names for DWIM logic' '
+	GIT_COMPLETION_CHECKOUT_NO_GUESS=1 test_completion "git switch --guess " <<-\EOF
+	branch-in-other Z
+	master Z
+	master-in-other Z
+	matching-branch Z
+	EOF
+'
+
+test_expect_success 'git switch - a later --guess overrides previous --no-guess, complete local and remote unique branches for DWIM' '
+	test_completion "git switch --no-guess --guess " <<-\EOF
+	branch-in-other Z
+	master Z
+	master-in-other Z
+	matching-branch Z
+	EOF
+'
+
+test_expect_success 'git switch - a later --no-guess overrides previous --guess, complete only local branches' '
+	test_completion "git switch --guess --no-guess " <<-\EOF
+	master Z
+	matching-branch Z
+	EOF
+'
+
+test_expect_success 'git checkout - with GIT_COMPLETION_NO_GUESS=1 only completes refs' '
+	GIT_COMPLETION_CHECKOUT_NO_GUESS=1 test_completion "git checkout " <<-\EOF
+	HEAD Z
+	master Z
+	matching-branch Z
+	matching-tag Z
+	other/branch-in-other Z
+	other/master-in-other Z
+	EOF
+'
+
+test_expect_success 'git checkout - --guess overrides GIT_COMPLETION_NO_GUESS=1, complete refs and unique remote branches for DWIM' '
+	GIT_COMPLETION_CHECKOUT_NO_GUESS=1 test_completion "git checkout --guess " <<-\EOF
+	HEAD Z
+	branch-in-other Z
+	master Z
+	master-in-other Z
+	matching-branch Z
+	matching-tag Z
+	other/branch-in-other Z
+	other/master-in-other Z
+	EOF
+'
+
+test_expect_success 'git checkout - with --no-guess, only completes refs' '
+	test_completion "git checkout --no-guess " <<-\EOF
+	HEAD Z
+	master Z
+	matching-branch Z
+	matching-tag Z
+	other/branch-in-other Z
+	other/master-in-other Z
+	EOF
+'
+
+test_expect_success 'git checkout - a later --guess overrides previous --no-guess, complete refs and unique remote branches for DWIM' '
+	test_completion "git checkout --no-guess --guess " <<-\EOF
+	HEAD Z
+	branch-in-other Z
+	master Z
+	master-in-other Z
+	matching-branch Z
+	matching-tag Z
+	other/branch-in-other Z
+	other/master-in-other Z
+	EOF
+'
+
+test_expect_success 'git checkout - a later --no-guess overrides previous --guess, complete only refs' '
+	test_completion "git checkout --guess --no-guess " <<-\EOF
+	HEAD Z
+	master Z
+	matching-branch Z
+	matching-tag Z
+	other/branch-in-other Z
+	other/master-in-other Z
+	EOF
+'
+
+test_expect_success 'git switch - with --detach, complete all references' '
+	test_completion "git switch --detach " <<-\EOF
+	HEAD Z
+	master Z
+	matching-branch Z
+	matching-tag Z
+	other/branch-in-other Z
+	other/master-in-other Z
+	EOF
+'
+
+test_expect_success 'git checkout - with --detach, complete only references' '
+	test_completion "git checkout --detach " <<-\EOF
+	HEAD Z
+	master Z
+	matching-branch Z
+	matching-tag Z
+	other/branch-in-other Z
+	other/master-in-other Z
+	EOF
+'
+
+test_expect_success 'git switch - with -d, complete all references' '
+	test_completion "git switch -d " <<-\EOF
+	HEAD Z
+	master Z
+	matching-branch Z
+	matching-tag Z
+	other/branch-in-other Z
+	other/master-in-other Z
+	EOF
+'
+
+test_expect_success 'git checkout - with -d, complete only references' '
+	test_completion "git checkout -d " <<-\EOF
+	HEAD Z
+	master Z
+	matching-branch Z
+	matching-tag Z
+	other/branch-in-other Z
+	other/master-in-other Z
+	EOF
+'
+
+test_expect_success 'git switch - with --track, complete only remote branches' '
+	test_completion "git switch --track " <<-\EOF
+	other/branch-in-other Z
+	other/master-in-other Z
+	EOF
+'
+
+test_expect_success 'git checkout - with --track, complete only remote branches' '
+	test_completion "git checkout --track " <<-\EOF
+	other/branch-in-other Z
+	other/master-in-other Z
+	EOF
+'
+
+test_expect_success 'git switch - with --no-track, complete only local branch names' '
+	test_completion "git switch --no-track " <<-\EOF
+	master Z
+	matching-branch Z
+	EOF
+'
+
+test_expect_success 'git checkout - with --no-track, complete only local references' '
+	test_completion "git checkout --no-track " <<-\EOF
+	HEAD Z
+	master Z
+	matching-branch Z
+	matching-tag Z
+	other/branch-in-other Z
+	other/master-in-other Z
+	EOF
+'
+
+test_expect_success 'git switch - with -c, complete all references' '
+	test_completion "git switch -c new-branch " <<-\EOF
+	HEAD Z
+	master Z
+	matching-branch Z
+	matching-tag Z
+	other/branch-in-other Z
+	other/master-in-other Z
+	EOF
+'
+
+test_expect_success 'git switch - with -C, complete all references' '
+	test_completion "git switch -C new-branch " <<-\EOF
+	HEAD Z
+	master Z
+	matching-branch Z
+	matching-tag Z
+	other/branch-in-other Z
+	other/master-in-other Z
+	EOF
+'
+
+test_expect_success 'git switch - with -c and --track, complete all references' '
+	test_completion "git switch -c new-branch --track " <<-EOF
+	HEAD Z
+	master Z
+	matching-branch Z
+	matching-tag Z
+	other/branch-in-other Z
+	other/master-in-other Z
+	EOF
+'
+
+test_expect_success 'git switch - with -C and --track, complete all references' '
+	test_completion "git switch -C new-branch --track " <<-EOF
+	HEAD Z
+	master Z
+	matching-branch Z
+	matching-tag Z
+	other/branch-in-other Z
+	other/master-in-other Z
+	EOF
+'
+
+test_expect_success 'git switch - with -c and --no-track, complete all references' '
+	test_completion "git switch -c new-branch --no-track " <<-\EOF
+	HEAD Z
+	master Z
+	matching-branch Z
+	matching-tag Z
+	other/branch-in-other Z
+	other/master-in-other Z
+	EOF
+'
+
+test_expect_success 'git switch - with -C and --no-track, complete all references' '
+	test_completion "git switch -C new-branch --no-track " <<-\EOF
+	HEAD Z
+	master Z
+	matching-branch Z
+	matching-tag Z
+	other/branch-in-other Z
+	other/master-in-other Z
+	EOF
+'
+
+test_expect_success 'git checkout - with -b, complete all references' '
+	test_completion "git checkout -b new-branch " <<-\EOF
+	HEAD Z
+	master Z
+	matching-branch Z
+	matching-tag Z
+	other/branch-in-other Z
+	other/master-in-other Z
+	EOF
+'
+
+test_expect_success 'git checkout - with -B, complete all references' '
+	test_completion "git checkout -B new-branch " <<-\EOF
+	HEAD Z
+	master Z
+	matching-branch Z
+	matching-tag Z
+	other/branch-in-other Z
+	other/master-in-other Z
+	EOF
+'
+
+test_expect_success 'git checkout - with -b and --track, complete all references' '
+	test_completion "git checkout -b new-branch --track " <<-EOF
+	HEAD Z
+	master Z
+	matching-branch Z
+	matching-tag Z
+	other/branch-in-other Z
+	other/master-in-other Z
+	EOF
+'
+
+test_expect_success 'git checkout - with -B and --track, complete all references' '
+	test_completion "git checkout -B new-branch --track " <<-EOF
+	HEAD Z
+	master Z
+	matching-branch Z
+	matching-tag Z
+	other/branch-in-other Z
+	other/master-in-other Z
+	EOF
+'
+
+test_expect_success 'git checkout - with -b and --no-track, complete all references' '
+	test_completion "git checkout -b new-branch --no-track " <<-\EOF
+	HEAD Z
+	master Z
+	matching-branch Z
+	matching-tag Z
+	other/branch-in-other Z
+	other/master-in-other Z
+	EOF
+'
+
+test_expect_success 'git checkout - with -B and --no-track, complete all references' '
+	test_completion "git checkout -B new-branch --no-track " <<-\EOF
+	HEAD Z
+	master Z
+	matching-branch Z
+	matching-tag Z
+	other/branch-in-other Z
+	other/master-in-other Z
+	EOF
+'
+
+test_expect_success 'git switch - for -c, complete local branches and unique remote branches' '
+	test_completion "git switch -c " <<-\EOF
+	branch-in-other Z
+	master Z
+	master-in-other Z
+	matching-branch Z
+	EOF
+'
+
+test_expect_success 'git switch - for -C, complete local branches and unique remote branches' '
+	test_completion "git switch -C " <<-\EOF
+	branch-in-other Z
+	master Z
+	master-in-other Z
+	matching-branch Z
+	EOF
+'
+
+test_expect_success 'git switch - for -c with --no-guess, complete local branches only' '
+	test_completion "git switch --no-guess -c " <<-\EOF
+	master Z
+	matching-branch Z
+	EOF
+'
+
+test_expect_success 'git switch - for -C with --no-guess, complete local branches only' '
+	test_completion "git switch --no-guess -C " <<-\EOF
+	master Z
+	matching-branch Z
+	EOF
+'
+
+test_expect_success 'git switch - for -c with --no-track, complete local branches only' '
+	test_completion "git switch --no-track -c " <<-\EOF
+	master Z
+	matching-branch Z
+	EOF
+'
+
+test_expect_success 'git switch - for -C with --no-track, complete local branches only' '
+	test_completion "git switch --no-track -C " <<-\EOF
+	master Z
+	matching-branch Z
+	EOF
+'
+
+test_expect_success 'git checkout - for -b, complete local branches and unique remote branches' '
+	test_completion "git checkout -b " <<-\EOF
+	branch-in-other Z
+	master Z
+	master-in-other Z
+	matching-branch Z
+	EOF
+'
+
+test_expect_success 'git checkout - for -B, complete local branches and unique remote branches' '
+	test_completion "git checkout -B " <<-\EOF
+	branch-in-other Z
+	master Z
+	master-in-other Z
+	matching-branch Z
+	EOF
+'
+
+test_expect_success 'git checkout - for -b with --no-guess, complete local branches only' '
+	test_completion "git checkout --no-guess -b " <<-\EOF
+	master Z
+	matching-branch Z
+	EOF
+'
+
+test_expect_success 'git checkout - for -B with --no-guess, complete local branches only' '
+	test_completion "git checkout --no-guess -B " <<-\EOF
+	master Z
+	matching-branch Z
+	EOF
+'
+
+test_expect_success 'git checkout - for -b with --no-track, complete local branches only' '
+	test_completion "git checkout --no-track -b " <<-\EOF
+	master Z
+	matching-branch Z
+	EOF
+'
+
+test_expect_success 'git checkout - for -B with --no-track, complete local branches only' '
+	test_completion "git checkout --no-track -B " <<-\EOF
+	master Z
+	matching-branch Z
+	EOF
+'
+
+test_expect_success 'git switch - with --orphan completes local branch names and unique remote branch names' '
+	test_completion "git switch --orphan " <<-\EOF
+	branch-in-other Z
+	master Z
+	master-in-other Z
+	matching-branch Z
+	EOF
+'
+
+test_expect_success 'git switch - --orphan with branch already provided completes nothing else' '
+	test_completion "git switch --orphan master " <<-\EOF
+
+	EOF
+'
+
+test_expect_success 'git checkout - with --orphan completes local branch names and unique remote branch names' '
+	test_completion "git checkout --orphan " <<-\EOF
+	branch-in-other Z
+	master Z
+	master-in-other Z
+	matching-branch Z
+	EOF
+'
+
+test_expect_success 'git checkout - --orphan with branch already provided completes local refs for a start-point' '
+	test_completion "git checkout --orphan master " <<-\EOF
+	HEAD Z
+	master Z
+	matching-branch Z
+	matching-tag Z
+	other/branch-in-other Z
+	other/master-in-other Z
+	EOF
+'
+
 test_expect_success 'teardown after ref completion' '
 	git branch -d matching-branch &&
 	git tag -d matching-tag &&
diff --git a/transport-helper.c b/transport-helper.c
index a46afcb..93a6f50 100644
--- a/transport-helper.c
+++ b/transport-helper.c
@@ -410,10 +410,11 @@
 			exit(128);
 
 		if (skip_prefix(buf.buf, "lock ", &name)) {
-			if (transport->pack_lockfile)
+			if (transport->pack_lockfiles.nr)
 				warning(_("%s also locked %s"), data->name, name);
 			else
-				transport->pack_lockfile = xstrdup(name);
+				string_list_append(&transport->pack_lockfiles,
+						   name);
 		}
 		else if (data->check_connectivity &&
 			 data->transport_options.check_self_contained_and_connected &&
diff --git a/transport.c b/transport.c
index 7d50c50..6ee6771 100644
--- a/transport.c
+++ b/transport.c
@@ -378,7 +378,7 @@
 	refs = fetch_pack(&args, data->fd,
 			  refs_tmp ? refs_tmp : transport->remote_refs,
 			  to_fetch, nr_heads, &data->shallow,
-			  &transport->pack_lockfile, data->version);
+			  &transport->pack_lockfiles, data->version);
 
 	close(data->fd[0]);
 	close(data->fd[1]);
@@ -921,6 +921,7 @@
 	struct transport *ret = xcalloc(1, sizeof(*ret));
 
 	ret->progress = isatty(2);
+	string_list_init(&ret->pack_lockfiles, 1);
 
 	if (!remote)
 		BUG("No remote provided to transport_get()");
@@ -1316,10 +1317,11 @@
 
 void transport_unlock_pack(struct transport *transport)
 {
-	if (transport->pack_lockfile) {
-		unlink_or_warn(transport->pack_lockfile);
-		FREE_AND_NULL(transport->pack_lockfile);
-	}
+	int i;
+
+	for (i = 0; i < transport->pack_lockfiles.nr; i++)
+		unlink_or_warn(transport->pack_lockfiles.items[i].string);
+	string_list_clear(&transport->pack_lockfiles, 0);
 }
 
 int transport_connect(struct transport *transport, const char *name,
diff --git a/transport.h b/transport.h
index 4298c85..05efa72 100644
--- a/transport.h
+++ b/transport.h
@@ -5,8 +5,7 @@
 #include "run-command.h"
 #include "remote.h"
 #include "list-objects-filter-options.h"
-
-struct string_list;
+#include "string-list.h"
 
 struct git_transport_options {
 	unsigned thin : 1;
@@ -98,7 +97,8 @@
 	 */
 	const struct string_list *server_options;
 
-	char *pack_lockfile;
+	struct string_list pack_lockfiles;
+
 	signed verbose : 3;
 	/**
 	 * Transports should not set this directly, and should use this
diff --git a/upload-pack.c b/upload-pack.c
index 401c9e6..39d0cf0 100644
--- a/upload-pack.c
+++ b/upload-pack.c
@@ -42,60 +42,71 @@
 #define ALL_FLAGS (THEY_HAVE | OUR_REF | WANTED | COMMON_KNOWN | SHALLOW | \
 		NOT_SHALLOW | CLIENT_SHALLOW | HIDDEN_REF)
 
-static timestamp_t oldest_have;
+/* Enum for allowed unadvertised object request (UOR) */
+enum allow_uor {
+	/* Allow specifying sha1 if it is a ref tip. */
+	ALLOW_TIP_SHA1 = 0x01,
+	/* Allow request of a sha1 if it is reachable from a ref (possibly hidden ref). */
+	ALLOW_REACHABLE_SHA1 = 0x02,
+	/* Allow request of any sha1. Implies ALLOW_TIP_SHA1 and ALLOW_REACHABLE_SHA1. */
+	ALLOW_ANY_SHA1 = 0x07
+};
 
-static int multi_ack;
-static int no_done;
-static int use_thin_pack, use_ofs_delta, use_include_tag;
-static int no_progress, daemon_mode;
-/* Allow specifying sha1 if it is a ref tip. */
-#define ALLOW_TIP_SHA1	01
-/* Allow request of a sha1 if it is reachable from a ref (possibly hidden ref). */
-#define ALLOW_REACHABLE_SHA1	02
-/* Allow request of any sha1. Implies ALLOW_TIP_SHA1 and ALLOW_REACHABLE_SHA1. */
-#define ALLOW_ANY_SHA1	07
-static unsigned int allow_unadvertised_object_request;
-static int shallow_nr;
-static struct object_array extra_edge_obj;
-static unsigned int timeout;
-static int keepalive = 5;
-/* 0 for no sideband,
- * otherwise maximum packet size (up to 65520 bytes).
+/*
+ * Please annotate, and if possible group together, fields used only
+ * for protocol v0 or only for protocol v2.
  */
-static int use_sideband;
-static const char *pack_objects_hook;
-
-static int filter_capability_requested;
-static int allow_filter;
-static int allow_ref_in_want;
-
-static int allow_sideband_all;
-
 struct upload_pack_data {
-	struct string_list symref;
-	struct string_list wanted_refs;
+	struct string_list symref;				/* v0 only */
 	struct object_array want_obj;
 	struct object_array have_obj;
-	struct oid_array haves;
+	struct oid_array haves;					/* v2 only */
+	struct string_list wanted_refs;				/* v2 only */
 
 	struct object_array shallows;
 	struct string_list deepen_not;
+	struct object_array extra_edge_obj;
 	int depth;
 	timestamp_t deepen_since;
 	int deepen_rev_list;
 	int deepen_relative;
+	int keepalive;
+	int shallow_nr;
+	timestamp_t oldest_have;
+
+	unsigned int timeout;					/* v0 only */
+	enum {
+		NO_MULTI_ACK = 0,
+		MULTI_ACK = 1,
+		MULTI_ACK_DETAILED = 2
+	} multi_ack;						/* v0 only */
+
+	/* 0 for no sideband, otherwise DEFAULT_PACKET_MAX or LARGE_PACKET_MAX */
+	int use_sideband;
+
+	struct string_list uri_protocols;
+	enum allow_uor allow_uor;
 
 	struct list_objects_filter_options filter_options;
 
 	struct packet_writer writer;
 
-	unsigned stateless_rpc : 1;
+	const char *pack_objects_hook;
+
+	unsigned stateless_rpc : 1;				/* v0 only */
+	unsigned no_done : 1;					/* v0 only */
+	unsigned daemon_mode : 1;				/* v0 only */
+	unsigned filter_capability_requested : 1;		/* v0 only */
 
 	unsigned use_thin_pack : 1;
 	unsigned use_ofs_delta : 1;
 	unsigned no_progress : 1;
 	unsigned use_include_tag : 1;
-	unsigned done : 1;
+	unsigned allow_filter : 1;
+
+	unsigned done : 1;					/* v2 only */
+	unsigned allow_ref_in_want : 1;				/* v2 only */
+	unsigned allow_sideband_all : 1;			/* v2 only */
 };
 
 static void upload_pack_data_init(struct upload_pack_data *data)
@@ -107,6 +118,8 @@
 	struct oid_array haves = OID_ARRAY_INIT;
 	struct object_array shallows = OBJECT_ARRAY_INIT;
 	struct string_list deepen_not = STRING_LIST_INIT_DUP;
+	struct string_list uri_protocols = STRING_LIST_INIT_DUP;
+	struct object_array extra_edge_obj = OBJECT_ARRAY_INIT;
 
 	memset(data, 0, sizeof(*data));
 	data->symref = symref;
@@ -116,7 +129,11 @@
 	data->haves = haves;
 	data->shallows = shallows;
 	data->deepen_not = deepen_not;
+	data->uri_protocols = uri_protocols;
+	data->extra_edge_obj = extra_edge_obj;
 	packet_writer_init(&data->writer, 1);
+
+	data->keepalive = 5;
 }
 
 static void upload_pack_data_clear(struct upload_pack_data *data)
@@ -128,15 +145,19 @@
 	oid_array_clear(&data->haves);
 	object_array_clear(&data->shallows);
 	string_list_clear(&data->deepen_not, 0);
+	object_array_clear(&data->extra_edge_obj);
 	list_objects_filter_release(&data->filter_options);
+
+	free((char *)data->pack_objects_hook);
 }
 
-static void reset_timeout(void)
+static void reset_timeout(unsigned int timeout)
 {
 	alarm(timeout);
 }
 
-static void send_client_data(int fd, const char *data, ssize_t sz)
+static void send_client_data(int fd, const char *data, ssize_t sz,
+			     int use_sideband)
 {
 	if (use_sideband) {
 		send_sideband(1, fd, data, sz, use_sideband);
@@ -161,42 +182,115 @@
 	return 0;
 }
 
-static void create_pack_file(struct upload_pack_data *pack_data)
+struct output_state {
+	char buffer[8193];
+	int used;
+	unsigned packfile_uris_started : 1;
+	unsigned packfile_started : 1;
+};
+
+static int relay_pack_data(int pack_objects_out, struct output_state *os,
+			   int use_sideband, int write_packfile_line)
+{
+	/*
+	 * We keep the last byte to ourselves
+	 * in case we detect broken rev-list, so that we
+	 * can leave the stream corrupted.  This is
+	 * unfortunate -- unpack-objects would happily
+	 * accept a valid packdata with trailing garbage,
+	 * so appending garbage after we pass all the
+	 * pack data is not good enough to signal
+	 * breakage to downstream.
+	 */
+	ssize_t readsz;
+
+	readsz = xread(pack_objects_out, os->buffer + os->used,
+		       sizeof(os->buffer) - os->used);
+	if (readsz < 0) {
+		return readsz;
+	}
+	os->used += readsz;
+
+	while (!os->packfile_started) {
+		char *p;
+		if (os->used >= 4 && !memcmp(os->buffer, "PACK", 4)) {
+			os->packfile_started = 1;
+			if (write_packfile_line) {
+				if (os->packfile_uris_started)
+					packet_delim(1);
+				packet_write_fmt(1, "\1packfile\n");
+			}
+			break;
+		}
+		if ((p = memchr(os->buffer, '\n', os->used))) {
+			if (!os->packfile_uris_started) {
+				os->packfile_uris_started = 1;
+				if (!write_packfile_line)
+					BUG("packfile_uris requires sideband-all");
+				packet_write_fmt(1, "\1packfile-uris\n");
+			}
+			*p = '\0';
+			packet_write_fmt(1, "\1%s\n", os->buffer);
+
+			os->used -= p - os->buffer + 1;
+			memmove(os->buffer, p + 1, os->used);
+		} else {
+			/*
+			 * Incomplete line.
+			 */
+			return readsz;
+		}
+	}
+
+	if (os->used > 1) {
+		send_client_data(1, os->buffer, os->used - 1, use_sideband);
+		os->buffer[0] = os->buffer[os->used - 1];
+		os->used = 1;
+	} else {
+		send_client_data(1, os->buffer, os->used, use_sideband);
+		os->used = 0;
+	}
+
+	return readsz;
+}
+
+static void create_pack_file(struct upload_pack_data *pack_data,
+			     const struct string_list *uri_protocols)
 {
 	struct child_process pack_objects = CHILD_PROCESS_INIT;
-	char data[8193], progress[128];
+	struct output_state output_state = { { 0 } };
+	char progress[128];
 	char abort_msg[] = "aborting due to possible repository "
 		"corruption on the remote side.";
-	int buffered = -1;
 	ssize_t sz;
 	int i;
 	FILE *pipe_fd;
 
-	if (!pack_objects_hook)
+	if (!pack_data->pack_objects_hook)
 		pack_objects.git_cmd = 1;
 	else {
-		argv_array_push(&pack_objects.args, pack_objects_hook);
+		argv_array_push(&pack_objects.args, pack_data->pack_objects_hook);
 		argv_array_push(&pack_objects.args, "git");
 		pack_objects.use_shell = 1;
 	}
 
-	if (shallow_nr) {
+	if (pack_data->shallow_nr) {
 		argv_array_push(&pack_objects.args, "--shallow-file");
 		argv_array_push(&pack_objects.args, "");
 	}
 	argv_array_push(&pack_objects.args, "pack-objects");
 	argv_array_push(&pack_objects.args, "--revs");
-	if (use_thin_pack)
+	if (pack_data->use_thin_pack)
 		argv_array_push(&pack_objects.args, "--thin");
 
 	argv_array_push(&pack_objects.args, "--stdout");
-	if (shallow_nr)
+	if (pack_data->shallow_nr)
 		argv_array_push(&pack_objects.args, "--shallow");
-	if (!no_progress)
+	if (!pack_data->no_progress)
 		argv_array_push(&pack_objects.args, "--progress");
-	if (use_ofs_delta)
+	if (pack_data->use_ofs_delta)
 		argv_array_push(&pack_objects.args, "--delta-base-offset");
-	if (use_include_tag)
+	if (pack_data->use_include_tag)
 		argv_array_push(&pack_objects.args, "--include-tag");
 	if (pack_data->filter_options.choice) {
 		const char *spec =
@@ -211,6 +305,11 @@
 					 spec);
 		}
 	}
+	if (uri_protocols) {
+		for (i = 0; i < uri_protocols->nr; i++)
+			argv_array_pushf(&pack_objects.args, "--uri-protocol=%s",
+					 uri_protocols->items[i].string);
+	}
 
 	pack_objects.in = -1;
 	pack_objects.out = -1;
@@ -221,7 +320,7 @@
 
 	pipe_fd = xfdopen(pack_objects.in, "w");
 
-	if (shallow_nr)
+	if (pack_data->shallow_nr)
 		for_each_commit_graft(write_one_shallow, pipe_fd);
 
 	for (i = 0; i < pack_data->want_obj.nr; i++)
@@ -231,9 +330,9 @@
 	for (i = 0; i < pack_data->have_obj.nr; i++)
 		fprintf(pipe_fd, "%s\n",
 			oid_to_hex(&pack_data->have_obj.objects[i].item->oid));
-	for (i = 0; i < extra_edge_obj.nr; i++)
+	for (i = 0; i < pack_data->extra_edge_obj.nr; i++)
 		fprintf(pipe_fd, "%s\n",
-			oid_to_hex(&extra_edge_obj.objects[i].item->oid));
+			oid_to_hex(&pack_data->extra_edge_obj.objects[i].item->oid));
 	fprintf(pipe_fd, "\n");
 	fflush(pipe_fd);
 	fclose(pipe_fd);
@@ -244,10 +343,10 @@
 
 	while (1) {
 		struct pollfd pfd[2];
-		int pe, pu, pollsize;
+		int pe, pu, pollsize, polltimeout;
 		int ret;
 
-		reset_timeout();
+		reset_timeout(pack_data->timeout);
 
 		pollsize = 0;
 		pe = pu = -1;
@@ -268,8 +367,11 @@
 		if (!pollsize)
 			break;
 
-		ret = poll(pfd, pollsize,
-			keepalive < 0 ? -1 : 1000 * keepalive);
+		polltimeout = pack_data->keepalive < 0
+			? -1
+			: 1000 * pack_data->keepalive;
+
+		ret = poll(pfd, pollsize, polltimeout);
 
 		if (ret < 0) {
 			if (errno != EINTR) {
@@ -285,7 +387,8 @@
 			sz = xread(pack_objects.err, progress,
 				  sizeof(progress));
 			if (0 < sz)
-				send_client_data(2, progress, sz);
+				send_client_data(2, progress, sz,
+						 pack_data->use_sideband);
 			else if (sz == 0) {
 				close(pack_objects.err);
 				pack_objects.err = -1;
@@ -296,39 +399,17 @@
 			continue;
 		}
 		if (0 <= pu && (pfd[pu].revents & (POLLIN|POLLHUP))) {
-			/* Data ready; we keep the last byte to ourselves
-			 * in case we detect broken rev-list, so that we
-			 * can leave the stream corrupted.  This is
-			 * unfortunate -- unpack-objects would happily
-			 * accept a valid packdata with trailing garbage,
-			 * so appending garbage after we pass all the
-			 * pack data is not good enough to signal
-			 * breakage to downstream.
-			 */
-			char *cp = data;
-			ssize_t outsz = 0;
-			if (0 <= buffered) {
-				*cp++ = buffered;
-				outsz++;
-			}
-			sz = xread(pack_objects.out, cp,
-				  sizeof(data) - outsz);
-			if (0 < sz)
-				;
-			else if (sz == 0) {
+			int result = relay_pack_data(pack_objects.out,
+						     &output_state,
+						     pack_data->use_sideband,
+						     !!uri_protocols);
+
+			if (result == 0) {
 				close(pack_objects.out);
 				pack_objects.out = -1;
-			}
-			else
+			} else if (result < 0) {
 				goto fail;
-			sz += outsz;
-			if (1 < sz) {
-				buffered = data[sz-1] & 0xFF;
-				sz--;
 			}
-			else
-				buffered = -1;
-			send_client_data(1, data, sz);
 		}
 
 		/*
@@ -341,7 +422,7 @@
 		 * protocol to say anything, so those clients are just out of
 		 * luck.
 		 */
-		if (!ret && use_sideband) {
+		if (!ret && pack_data->use_sideband) {
 			static const char buf[] = "0005\1";
 			write_or_die(1, buf, 5);
 		}
@@ -353,32 +434,26 @@
 	}
 
 	/* flush the data */
-	if (0 <= buffered) {
-		data[0] = buffered;
-		send_client_data(1, data, 1);
+	if (output_state.used > 0) {
+		send_client_data(1, output_state.buffer, output_state.used,
+				 pack_data->use_sideband);
 		fprintf(stderr, "flushed.\n");
 	}
-	if (use_sideband)
+	if (pack_data->use_sideband)
 		packet_flush(1);
 	return;
 
  fail:
-	send_client_data(3, abort_msg, sizeof(abort_msg));
+	send_client_data(3, abort_msg, sizeof(abort_msg),
+			 pack_data->use_sideband);
 	die("git upload-pack: %s", abort_msg);
 }
 
-static int got_oid(const char *hex, struct object_id *oid,
-		   struct object_array *have_obj)
+static int do_got_oid(struct upload_pack_data *data, const struct object_id *oid)
 {
-	struct object *o;
 	int we_knew_they_have = 0;
+	struct object *o = parse_object(the_repository, oid);
 
-	if (get_oid_hex(hex, oid))
-		die("git upload-pack: expected SHA1 object, got '%s'", hex);
-	if (!has_object_file(oid))
-		return -1;
-
-	o = parse_object(the_repository, oid);
 	if (!o)
 		die("oops (%s)", oid_to_hex(oid));
 	if (o->type == OBJ_COMMIT) {
@@ -388,30 +463,39 @@
 			we_knew_they_have = 1;
 		else
 			o->flags |= THEY_HAVE;
-		if (!oldest_have || (commit->date < oldest_have))
-			oldest_have = commit->date;
+		if (!data->oldest_have || (commit->date < data->oldest_have))
+			data->oldest_have = commit->date;
 		for (parents = commit->parents;
 		     parents;
 		     parents = parents->next)
 			parents->item->object.flags |= THEY_HAVE;
 	}
 	if (!we_knew_they_have) {
-		add_object_array(o, NULL, have_obj);
+		add_object_array(o, NULL, &data->have_obj);
 		return 1;
 	}
 	return 0;
 }
 
-static int ok_to_give_up(const struct object_array *have_obj,
-			 struct object_array *want_obj)
+static int got_oid(struct upload_pack_data *data,
+		   const char *hex, struct object_id *oid)
+{
+	if (get_oid_hex(hex, oid))
+		die("git upload-pack: expected SHA1 object, got '%s'", hex);
+	if (!has_object_file(oid))
+		return -1;
+	return do_got_oid(data, oid);
+}
+
+static int ok_to_give_up(struct upload_pack_data *data)
 {
 	uint32_t min_generation = GENERATION_NUMBER_ZERO;
 
-	if (!have_obj->nr)
+	if (!data->have_obj.nr)
 		return 0;
 
-	return can_all_from_reach_with_flag(want_obj, THEY_HAVE,
-					    COMMON_KNOWN, oldest_have,
+	return can_all_from_reach_with_flag(&data->want_obj, THEY_HAVE,
+					    COMMON_KNOWN, data->oldest_have,
 					    min_generation);
 }
 
@@ -429,20 +513,20 @@
 	for (;;) {
 		const char *arg;
 
-		reset_timeout();
+		reset_timeout(data->timeout);
 
 		if (packet_reader_read(reader) != PACKET_READ_NORMAL) {
-			if (multi_ack == 2
+			if (data->multi_ack == MULTI_ACK_DETAILED
 			    && got_common
 			    && !got_other
-			    && ok_to_give_up(&data->have_obj, &data->want_obj)) {
+			    && ok_to_give_up(data)) {
 				sent_ready = 1;
 				packet_write_fmt(1, "ACK %s ready\n", last_hex);
 			}
-			if (data->have_obj.nr == 0 || multi_ack)
+			if (data->have_obj.nr == 0 || data->multi_ack)
 				packet_write_fmt(1, "NAK\n");
 
-			if (no_done && sent_ready) {
+			if (data->no_done && sent_ready) {
 				packet_write_fmt(1, "ACK %s\n", last_hex);
 				return 0;
 			}
@@ -453,13 +537,13 @@
 			continue;
 		}
 		if (skip_prefix(reader->line, "have ", &arg)) {
-			switch (got_oid(arg, &oid, &data->have_obj)) {
+			switch (got_oid(data, arg, &oid)) {
 			case -1: /* they have what we do not */
 				got_other = 1;
-				if (multi_ack
-				    && ok_to_give_up(&data->have_obj, &data->want_obj)) {
+				if (data->multi_ack
+				    && ok_to_give_up(data)) {
 					const char *hex = oid_to_hex(&oid);
-					if (multi_ack == 2) {
+					if (data->multi_ack == MULTI_ACK_DETAILED) {
 						sent_ready = 1;
 						packet_write_fmt(1, "ACK %s ready\n", hex);
 					} else
@@ -469,9 +553,9 @@
 			default:
 				got_common = 1;
 				oid_to_hex_r(last_hex, &oid);
-				if (multi_ack == 2)
+				if (data->multi_ack == MULTI_ACK_DETAILED)
 					packet_write_fmt(1, "ACK %s common\n", last_hex);
-				else if (multi_ack)
+				else if (data->multi_ack)
 					packet_write_fmt(1, "ACK %s continue\n", last_hex);
 				else if (data->have_obj.nr == 1)
 					packet_write_fmt(1, "ACK %s\n", last_hex);
@@ -481,7 +565,7 @@
 		}
 		if (!strcmp(reader->line, "done")) {
 			if (data->have_obj.nr > 0) {
-				if (multi_ack)
+				if (data->multi_ack)
 					packet_write_fmt(1, "ACK %s\n", last_hex);
 				return 0;
 			}
@@ -492,10 +576,10 @@
 	}
 }
 
-static int is_our_ref(struct object *o)
+static int is_our_ref(struct object *o, enum allow_uor allow_uor)
 {
-	int allow_hidden_ref = (allow_unadvertised_object_request &
-			(ALLOW_TIP_SHA1 | ALLOW_REACHABLE_SHA1));
+	int allow_hidden_ref = (allow_uor &
+				(ALLOW_TIP_SHA1 | ALLOW_REACHABLE_SHA1));
 	return o->flags & ((allow_hidden_ref ? HIDDEN_REF : 0) | OUR_REF);
 }
 
@@ -504,7 +588,8 @@
  */
 static int do_reachable_revlist(struct child_process *cmd,
 				struct object_array *src,
-				struct object_array *reachable)
+				struct object_array *reachable,
+				enum allow_uor allow_uor)
 {
 	static const char *argv[] = {
 		"rev-list", "--stdin", NULL,
@@ -538,7 +623,7 @@
 			continue;
 		if (reachable && o->type == OBJ_COMMIT)
 			o->flags &= ~TMP_MARK;
-		if (!is_our_ref(o))
+		if (!is_our_ref(o, allow_uor))
 			continue;
 		memcpy(namebuf + 1, oid_to_hex(&o->oid), hexsz);
 		if (write_in_full(cmd->in, namebuf, hexsz + 2) < 0)
@@ -547,7 +632,7 @@
 	namebuf[hexsz] = '\n';
 	for (i = 0; i < src->nr; i++) {
 		o = src->objects[i].item;
-		if (is_our_ref(o)) {
+		if (is_our_ref(o, allow_uor)) {
 			if (reachable)
 				add_object_array(o, NULL, reachable);
 			continue;
@@ -574,7 +659,7 @@
 	return -1;
 }
 
-static int get_reachable_list(struct object_array *src,
+static int get_reachable_list(struct upload_pack_data *data,
 			      struct object_array *reachable)
 {
 	struct child_process cmd = CHILD_PROCESS_INIT;
@@ -583,7 +668,8 @@
 	char namebuf[GIT_MAX_HEXSZ + 2]; /* ^ + hash + LF */
 	const unsigned hexsz = the_hash_algo->hexsz;
 
-	if (do_reachable_revlist(&cmd, src, reachable) < 0)
+	if (do_reachable_revlist(&cmd, &data->shallows, reachable,
+				 data->allow_uor) < 0)
 		return -1;
 
 	while ((i = read_in_full(cmd.out, namebuf, hexsz + 1)) == hexsz + 1) {
@@ -614,13 +700,13 @@
 	return 0;
 }
 
-static int has_unreachable(struct object_array *src)
+static int has_unreachable(struct object_array *src, enum allow_uor allow_uor)
 {
 	struct child_process cmd = CHILD_PROCESS_INIT;
 	char buf[1];
 	int i;
 
-	if (do_reachable_revlist(&cmd, src, NULL) < 0)
+	if (do_reachable_revlist(&cmd, src, NULL, allow_uor) < 0)
 		return 1;
 
 	/*
@@ -660,10 +746,9 @@
 	 * uploadpack.allowReachableSHA1InWant,
 	 * non-tip requests can never happen.
 	 */
-	if (!data->stateless_rpc
-	    && !(allow_unadvertised_object_request & ALLOW_REACHABLE_SHA1))
+	if (!data->stateless_rpc && !(data->allow_uor & ALLOW_REACHABLE_SHA1))
 		goto error;
-	if (!has_unreachable(&data->want_obj))
+	if (!has_unreachable(&data->want_obj, data->allow_uor))
 		/* All the non-tip ones are ancestors of what we advertised */
 		return;
 
@@ -671,7 +756,7 @@
 	/* Pick one of them (we know there at least is one) */
 	for (i = 0; i < data->want_obj.nr; i++) {
 		struct object *o = data->want_obj.objects[i].item;
-		if (!is_our_ref(o)) {
+		if (!is_our_ref(o, data->allow_uor)) {
 			packet_writer_error(&data->writer,
 					    "upload-pack: not our ref %s",
 					    oid_to_hex(&o->oid));
@@ -681,32 +766,30 @@
 	}
 }
 
-static void send_shallow(struct packet_writer *writer,
+static void send_shallow(struct upload_pack_data *data,
 			 struct commit_list *result)
 {
 	while (result) {
 		struct object *object = &result->item->object;
 		if (!(object->flags & (CLIENT_SHALLOW|NOT_SHALLOW))) {
-			packet_writer_write(writer, "shallow %s",
+			packet_writer_write(&data->writer, "shallow %s",
 					    oid_to_hex(&object->oid));
 			register_shallow(the_repository, &object->oid);
-			shallow_nr++;
+			data->shallow_nr++;
 		}
 		result = result->next;
 	}
 }
 
-static void send_unshallow(struct packet_writer *writer,
-			   const struct object_array *shallows,
-			   struct object_array *want_obj)
+static void send_unshallow(struct upload_pack_data *data)
 {
 	int i;
 
-	for (i = 0; i < shallows->nr; i++) {
-		struct object *object = shallows->objects[i].item;
+	for (i = 0; i < data->shallows.nr; i++) {
+		struct object *object = data->shallows.objects[i].item;
 		if (object->flags & NOT_SHALLOW) {
 			struct commit_list *parents;
-			packet_writer_write(writer, "unshallow %s",
+			packet_writer_write(&data->writer, "unshallow %s",
 					    oid_to_hex(&object->oid));
 			object->flags &= ~CLIENT_SHALLOW;
 			/*
@@ -722,10 +805,10 @@
 			parents = ((struct commit *)object)->parents;
 			while (parents) {
 				add_object_array(&parents->item->object,
-						 NULL, want_obj);
+						 NULL, &data->want_obj);
 				parents = parents->next;
 			}
-			add_object_array(object, NULL, &extra_edge_obj);
+			add_object_array(object, NULL, &data->extra_edge_obj);
 		}
 		/* make sure commit traversal conforms to client */
 		register_shallow(the_repository, &object->oid);
@@ -734,17 +817,16 @@
 
 static int check_ref(const char *refname_full, const struct object_id *oid,
 		     int flag, void *cb_data);
-static void deepen(struct packet_writer *writer, int depth, int deepen_relative,
-		   struct object_array *shallows, struct object_array *want_obj)
+static void deepen(struct upload_pack_data *data, int depth)
 {
 	if (depth == INFINITE_DEPTH && !is_repository_shallow(the_repository)) {
 		int i;
 
-		for (i = 0; i < shallows->nr; i++) {
-			struct object *object = shallows->objects[i].item;
+		for (i = 0; i < data->shallows.nr; i++) {
+			struct object *object = data->shallows.objects[i].item;
 			object->flags |= NOT_SHALLOW;
 		}
-	} else if (deepen_relative) {
+	} else if (data->deepen_relative) {
 		struct object_array reachable_shallows = OBJECT_ARRAY_INIT;
 		struct commit_list *result;
 
@@ -755,87 +837,80 @@
 		head_ref_namespaced(check_ref, NULL);
 		for_each_namespaced_ref(check_ref, NULL);
 
-		get_reachable_list(shallows, &reachable_shallows);
+		get_reachable_list(data, &reachable_shallows);
 		result = get_shallow_commits(&reachable_shallows,
 					     depth + 1,
 					     SHALLOW, NOT_SHALLOW);
-		send_shallow(writer, result);
+		send_shallow(data, result);
 		free_commit_list(result);
 		object_array_clear(&reachable_shallows);
 	} else {
 		struct commit_list *result;
 
-		result = get_shallow_commits(want_obj, depth,
+		result = get_shallow_commits(&data->want_obj, depth,
 					     SHALLOW, NOT_SHALLOW);
-		send_shallow(writer, result);
+		send_shallow(data, result);
 		free_commit_list(result);
 	}
 
-	send_unshallow(writer, shallows, want_obj);
+	send_unshallow(data);
 }
 
-static void deepen_by_rev_list(struct packet_writer *writer, int ac,
-			       const char **av,
-			       struct object_array *shallows,
-			       struct object_array *want_obj)
+static void deepen_by_rev_list(struct upload_pack_data *data,
+			       int ac,
+			       const char **av)
 {
 	struct commit_list *result;
 
 	disable_commit_graph(the_repository);
 	result = get_shallow_commits_by_rev_list(ac, av, SHALLOW, NOT_SHALLOW);
-	send_shallow(writer, result);
+	send_shallow(data, result);
 	free_commit_list(result);
-	send_unshallow(writer, shallows, want_obj);
+	send_unshallow(data);
 }
 
 /* Returns 1 if a shallow list is sent or 0 otherwise */
-static int send_shallow_list(struct packet_writer *writer,
-			     int depth, int deepen_rev_list,
-			     timestamp_t deepen_since,
-			     struct string_list *deepen_not,
-			     int deepen_relative,
-			     struct object_array *shallows,
-			     struct object_array *want_obj)
+static int send_shallow_list(struct upload_pack_data *data)
 {
 	int ret = 0;
 
-	if (depth > 0 && deepen_rev_list)
+	if (data->depth > 0 && data->deepen_rev_list)
 		die("git upload-pack: deepen and deepen-since (or deepen-not) cannot be used together");
-	if (depth > 0) {
-		deepen(writer, depth, deepen_relative, shallows, want_obj);
+	if (data->depth > 0) {
+		deepen(data, data->depth);
 		ret = 1;
-	} else if (deepen_rev_list) {
+	} else if (data->deepen_rev_list) {
 		struct argv_array av = ARGV_ARRAY_INIT;
 		int i;
 
 		argv_array_push(&av, "rev-list");
-		if (deepen_since)
-			argv_array_pushf(&av, "--max-age=%"PRItime, deepen_since);
-		if (deepen_not->nr) {
+		if (data->deepen_since)
+			argv_array_pushf(&av, "--max-age=%"PRItime, data->deepen_since);
+		if (data->deepen_not.nr) {
 			argv_array_push(&av, "--not");
-			for (i = 0; i < deepen_not->nr; i++) {
-				struct string_list_item *s = deepen_not->items + i;
+			for (i = 0; i < data->deepen_not.nr; i++) {
+				struct string_list_item *s = data->deepen_not.items + i;
 				argv_array_push(&av, s->string);
 			}
 			argv_array_push(&av, "--not");
 		}
-		for (i = 0; i < want_obj->nr; i++) {
-			struct object *o = want_obj->objects[i].item;
+		for (i = 0; i < data->want_obj.nr; i++) {
+			struct object *o = data->want_obj.objects[i].item;
 			argv_array_push(&av, oid_to_hex(&o->oid));
 		}
-		deepen_by_rev_list(writer, av.argc, av.argv, shallows, want_obj);
+		deepen_by_rev_list(data, av.argc, av.argv);
 		argv_array_clear(&av);
 		ret = 1;
 	} else {
-		if (shallows->nr > 0) {
+		if (data->shallows.nr > 0) {
 			int i;
-			for (i = 0; i < shallows->nr; i++)
+			for (i = 0; i < data->shallows.nr; i++)
 				register_shallow(the_repository,
-						 &shallows->objects[i].item->oid);
+						 &data->shallows.objects[i].item->oid);
 		}
 	}
 
-	shallow_nr += shallows->nr;
+	data->shallow_nr += data->shallows.nr;
 	return ret;
 }
 
@@ -913,14 +988,14 @@
 {
 	int has_non_tip = 0;
 
-	shallow_nr = 0;
+	data->shallow_nr = 0;
 	for (;;) {
 		struct object *o;
 		const char *features;
 		struct object_id oid_buf;
 		const char *arg;
 
-		reset_timeout();
+		reset_timeout(data->timeout);
 		if (packet_reader_read(reader) != PACKET_READ_NORMAL)
 			break;
 
@@ -934,7 +1009,7 @@
 			continue;
 
 		if (skip_prefix(reader->line, "filter ", &arg)) {
-			if (!filter_capability_requested)
+			if (!data->filter_capability_requested)
 				die("git upload-pack: filtering capability not negotiated");
 			list_objects_filter_die_if_populated(&data->filter_options);
 			parse_list_objects_filter(&data->filter_options, arg);
@@ -949,25 +1024,26 @@
 		if (parse_feature_request(features, "deepen-relative"))
 			data->deepen_relative = 1;
 		if (parse_feature_request(features, "multi_ack_detailed"))
-			multi_ack = 2;
+			data->multi_ack = MULTI_ACK_DETAILED;
 		else if (parse_feature_request(features, "multi_ack"))
-			multi_ack = 1;
+			data->multi_ack = MULTI_ACK;
 		if (parse_feature_request(features, "no-done"))
-			no_done = 1;
+			data->no_done = 1;
 		if (parse_feature_request(features, "thin-pack"))
-			use_thin_pack = 1;
+			data->use_thin_pack = 1;
 		if (parse_feature_request(features, "ofs-delta"))
-			use_ofs_delta = 1;
+			data->use_ofs_delta = 1;
 		if (parse_feature_request(features, "side-band-64k"))
-			use_sideband = LARGE_PACKET_MAX;
+			data->use_sideband = LARGE_PACKET_MAX;
 		else if (parse_feature_request(features, "side-band"))
-			use_sideband = DEFAULT_PACKET_MAX;
+			data->use_sideband = DEFAULT_PACKET_MAX;
 		if (parse_feature_request(features, "no-progress"))
-			no_progress = 1;
+			data->no_progress = 1;
 		if (parse_feature_request(features, "include-tag"))
-			use_include_tag = 1;
-		if (allow_filter && parse_feature_request(features, "filter"))
-			filter_capability_requested = 1;
+			data->use_include_tag = 1;
+		if (data->allow_filter &&
+		    parse_feature_request(features, "filter"))
+			data->filter_capability_requested = 1;
 
 		o = parse_object(the_repository, &oid_buf);
 		if (!o) {
@@ -979,8 +1055,8 @@
 		}
 		if (!(o->flags & WANTED)) {
 			o->flags |= WANTED;
-			if (!((allow_unadvertised_object_request & ALLOW_ANY_SHA1) == ALLOW_ANY_SHA1
-			      || is_our_ref(o)))
+			if (!((data->allow_uor & ALLOW_ANY_SHA1) == ALLOW_ANY_SHA1
+			      || is_our_ref(o, data->allow_uor)))
 				has_non_tip = 1;
 			add_object_array(o, NULL, &data->want_obj);
 		}
@@ -996,20 +1072,13 @@
 	if (has_non_tip)
 		check_non_tip(data);
 
-	if (!use_sideband && daemon_mode)
-		no_progress = 1;
+	if (!data->use_sideband && data->daemon_mode)
+		data->no_progress = 1;
 
 	if (data->depth == 0 && !data->deepen_rev_list && data->shallows.nr == 0)
 		return;
 
-	if (send_shallow_list(&data->writer,
-			      data->depth,
-			      data->deepen_rev_list,
-			      data->deepen_since,
-			      &data->deepen_not,
-			      data->deepen_relative,
-			      &data->shallows,
-			      &data->want_obj))
+	if (send_shallow_list(data))
 		packet_flush(1);
 }
 
@@ -1066,13 +1135,13 @@
 		packet_write_fmt(1, "%s %s%c%s%s%s%s%s%s agent=%s\n",
 			     oid_to_hex(oid), refname_nons,
 			     0, capabilities,
-			     (allow_unadvertised_object_request & ALLOW_TIP_SHA1) ?
+			     (data->allow_uor & ALLOW_TIP_SHA1) ?
 				     " allow-tip-sha1-in-want" : "",
-			     (allow_unadvertised_object_request & ALLOW_REACHABLE_SHA1) ?
+			     (data->allow_uor & ALLOW_REACHABLE_SHA1) ?
 				     " allow-reachable-sha1-in-want" : "",
 			     data->stateless_rpc ? " no-done" : "",
 			     symref_info.buf,
-			     allow_filter ? " filter" : "",
+			     data->allow_filter ? " filter" : "",
 			     git_user_agent_sanitized());
 		strbuf_release(&symref_info);
 	} else {
@@ -1100,33 +1169,35 @@
 	return 0;
 }
 
-static int upload_pack_config(const char *var, const char *value, void *unused)
+static int upload_pack_config(const char *var, const char *value, void *cb_data)
 {
+	struct upload_pack_data *data = cb_data;
+
 	if (!strcmp("uploadpack.allowtipsha1inwant", var)) {
 		if (git_config_bool(var, value))
-			allow_unadvertised_object_request |= ALLOW_TIP_SHA1;
+			data->allow_uor |= ALLOW_TIP_SHA1;
 		else
-			allow_unadvertised_object_request &= ~ALLOW_TIP_SHA1;
+			data->allow_uor &= ~ALLOW_TIP_SHA1;
 	} else if (!strcmp("uploadpack.allowreachablesha1inwant", var)) {
 		if (git_config_bool(var, value))
-			allow_unadvertised_object_request |= ALLOW_REACHABLE_SHA1;
+			data->allow_uor |= ALLOW_REACHABLE_SHA1;
 		else
-			allow_unadvertised_object_request &= ~ALLOW_REACHABLE_SHA1;
+			data->allow_uor &= ~ALLOW_REACHABLE_SHA1;
 	} else if (!strcmp("uploadpack.allowanysha1inwant", var)) {
 		if (git_config_bool(var, value))
-			allow_unadvertised_object_request |= ALLOW_ANY_SHA1;
+			data->allow_uor |= ALLOW_ANY_SHA1;
 		else
-			allow_unadvertised_object_request &= ~ALLOW_ANY_SHA1;
+			data->allow_uor &= ~ALLOW_ANY_SHA1;
 	} else if (!strcmp("uploadpack.keepalive", var)) {
-		keepalive = git_config_int(var, value);
-		if (!keepalive)
-			keepalive = -1;
+		data->keepalive = git_config_int(var, value);
+		if (!data->keepalive)
+			data->keepalive = -1;
 	} else if (!strcmp("uploadpack.allowfilter", var)) {
-		allow_filter = git_config_bool(var, value);
+		data->allow_filter = git_config_bool(var, value);
 	} else if (!strcmp("uploadpack.allowrefinwant", var)) {
-		allow_ref_in_want = git_config_bool(var, value);
+		data->allow_ref_in_want = git_config_bool(var, value);
 	} else if (!strcmp("uploadpack.allowsidebandall", var)) {
-		allow_sideband_all = git_config_bool(var, value);
+		data->allow_sideband_all = git_config_bool(var, value);
 	} else if (!strcmp("core.precomposeunicode", var)) {
 		precomposed_unicode = git_config_bool(var, value);
 	}
@@ -1134,7 +1205,7 @@
 	if (current_config_scope() != CONFIG_SCOPE_LOCAL &&
 	current_config_scope() != CONFIG_SCOPE_WORKTREE) {
 		if (!strcmp("uploadpack.packobjectshook", var))
-			return git_config_string(&pack_objects_hook, var, value);
+			return git_config_string(&data->pack_objects_hook, var, value);
 	}
 
 	return parse_hide_refs_config(var, value, "uploadpack");
@@ -1145,19 +1216,18 @@
 	struct packet_reader reader;
 	struct upload_pack_data data;
 
-	timeout = options->timeout;
-	daemon_mode = options->daemon_mode;
-
-	git_config(upload_pack_config, NULL);
-
 	upload_pack_data_init(&data);
 
+	git_config(upload_pack_config, &data);
+
 	data.stateless_rpc = options->stateless_rpc;
+	data.daemon_mode = options->daemon_mode;
+	data.timeout = options->timeout;
 
 	head_ref_namespaced(find_symref, &data.symref);
 
 	if (options->advertise_refs || !data.stateless_rpc) {
-		reset_timeout();
+		reset_timeout(data.timeout);
 		head_ref_namespaced(send_ref, &data);
 		for_each_namespaced_ref(send_ref, &data);
 		advertise_shallow_grafts(1);
@@ -1175,7 +1245,7 @@
 		receive_needs(&data, &reader);
 		if (data.want_obj.nr) {
 			get_common_commits(&data, &reader);
-			create_pack_file(&data);
+			create_pack_file(&data, NULL);
 		}
 	}
 
@@ -1269,7 +1339,7 @@
 		/* process want */
 		if (parse_want(&data->writer, arg, &data->want_obj))
 			continue;
-		if (allow_ref_in_want &&
+		if (data->allow_ref_in_want &&
 		    parse_want_ref(&data->writer, arg, &data->wanted_refs,
 				   &data->want_obj))
 			continue;
@@ -1279,19 +1349,19 @@
 
 		/* process args like thin-pack */
 		if (!strcmp(arg, "thin-pack")) {
-			use_thin_pack = 1;
+			data->use_thin_pack = 1;
 			continue;
 		}
 		if (!strcmp(arg, "ofs-delta")) {
-			use_ofs_delta = 1;
+			data->use_ofs_delta = 1;
 			continue;
 		}
 		if (!strcmp(arg, "no-progress")) {
-			no_progress = 1;
+			data->no_progress = 1;
 			continue;
 		}
 		if (!strcmp(arg, "include-tag")) {
-			use_include_tag = 1;
+			data->use_include_tag = 1;
 			continue;
 		}
 		if (!strcmp(arg, "done")) {
@@ -1315,87 +1385,72 @@
 			continue;
 		}
 
-		if (allow_filter && skip_prefix(arg, "filter ", &p)) {
+		if (data->allow_filter && skip_prefix(arg, "filter ", &p)) {
 			list_objects_filter_die_if_populated(&data->filter_options);
 			parse_list_objects_filter(&data->filter_options, p);
 			continue;
 		}
 
 		if ((git_env_bool("GIT_TEST_SIDEBAND_ALL", 0) ||
-		     allow_sideband_all) &&
+		     data->allow_sideband_all) &&
 		    !strcmp(arg, "sideband-all")) {
 			data->writer.use_sideband = 1;
 			continue;
 		}
 
+		if (skip_prefix(arg, "packfile-uris ", &p)) {
+			string_list_split(&data->uri_protocols, p, ',', -1);
+			continue;
+		}
+
 		/* ignore unknown lines maybe? */
 		die("unexpected line: '%s'", arg);
 	}
 
+	if (data->uri_protocols.nr && !data->writer.use_sideband)
+		string_list_clear(&data->uri_protocols, 0);
+
 	if (request->status != PACKET_READ_FLUSH)
 		die(_("expected flush after fetch arguments"));
 }
 
-static int process_haves(struct oid_array *haves, struct oid_array *common,
-			 struct object_array *have_obj)
+static int process_haves(struct upload_pack_data *data, struct oid_array *common)
 {
 	int i;
 
 	/* Process haves */
-	for (i = 0; i < haves->nr; i++) {
-		const struct object_id *oid = &haves->oid[i];
-		struct object *o;
-		int we_knew_they_have = 0;
+	for (i = 0; i < data->haves.nr; i++) {
+		const struct object_id *oid = &data->haves.oid[i];
 
 		if (!has_object_file(oid))
 			continue;
 
 		oid_array_append(common, oid);
 
-		o = parse_object(the_repository, oid);
-		if (!o)
-			die("oops (%s)", oid_to_hex(oid));
-		if (o->type == OBJ_COMMIT) {
-			struct commit_list *parents;
-			struct commit *commit = (struct commit *)o;
-			if (o->flags & THEY_HAVE)
-				we_knew_they_have = 1;
-			else
-				o->flags |= THEY_HAVE;
-			if (!oldest_have || (commit->date < oldest_have))
-				oldest_have = commit->date;
-			for (parents = commit->parents;
-			     parents;
-			     parents = parents->next)
-				parents->item->object.flags |= THEY_HAVE;
-		}
-		if (!we_knew_they_have)
-			add_object_array(o, NULL, have_obj);
+		do_got_oid(data, oid);
 	}
 
 	return 0;
 }
 
-static int send_acks(struct packet_writer *writer, struct oid_array *acks,
-		     const struct object_array *have_obj,
-		     struct object_array *want_obj)
+static int send_acks(struct upload_pack_data *data, struct oid_array *acks)
 {
 	int i;
 
-	packet_writer_write(writer, "acknowledgments\n");
+	packet_writer_write(&data->writer, "acknowledgments\n");
 
 	/* Send Acks */
 	if (!acks->nr)
-		packet_writer_write(writer, "NAK\n");
+		packet_writer_write(&data->writer, "NAK\n");
 
 	for (i = 0; i < acks->nr; i++) {
-		packet_writer_write(writer, "ACK %s\n",
+		packet_writer_write(&data->writer, "ACK %s\n",
 				    oid_to_hex(&acks->oid[i]));
 	}
 
-	if (ok_to_give_up(have_obj, want_obj)) {
+	if (ok_to_give_up(data)) {
 		/* Send Ready */
-		packet_writer_write(writer, "ready\n");
+		packet_writer_write(&data->writer, "ready\n");
 		return 1;
 	}
 
@@ -1407,11 +1462,10 @@
 	struct oid_array common = OID_ARRAY_INIT;
 	int ret = 0;
 
-	process_haves(&data->haves, &common, &data->have_obj);
+	process_haves(data, &common);
 	if (data->done) {
 		ret = 1;
-	} else if (send_acks(&data->writer, &common,
-			     &data->have_obj, &data->want_obj)) {
+	} else if (send_acks(data, &common)) {
 		packet_writer_delim(&data->writer);
 		ret = 1;
 	} else {
@@ -1452,14 +1506,9 @@
 
 	packet_writer_write(&data->writer, "shallow-info\n");
 
-	if (!send_shallow_list(&data->writer, data->depth,
-			       data->deepen_rev_list,
-			       data->deepen_since, &data->deepen_not,
-			       data->deepen_relative,
-			       &data->shallows, &data->want_obj) &&
+	if (!send_shallow_list(data) &&
 	    is_repository_shallow(the_repository))
-		deepen(&data->writer, INFINITE_DEPTH, data->deepen_relative,
-		       &data->shallows, &data->want_obj);
+		deepen(data, INFINITE_DEPTH);
 
 	packet_delim(1);
 }
@@ -1479,10 +1528,10 @@
 
 	clear_object_flags(ALL_FLAGS);
 
-	git_config(upload_pack_config, NULL);
-
 	upload_pack_data_init(&data);
-	use_sideband = LARGE_PACKET_MAX;
+	data.use_sideband = LARGE_PACKET_MAX;
+
+	git_config(upload_pack_config, &data);
 
 	while (state != FETCH_DONE) {
 		switch (state) {
@@ -1518,8 +1567,12 @@
 			send_wanted_ref_info(&data);
 			send_shallow_info(&data);
 
-			packet_writer_write(&data.writer, "packfile\n");
-			create_pack_file(&data);
+			if (data.uri_protocols.nr) {
+				create_pack_file(&data, &data.uri_protocols);
+			} else {
+				packet_writer_write(&data.writer, "packfile\n");
+				create_pack_file(&data, NULL);
+			}
 			state = FETCH_DONE;
 			break;
 		case FETCH_DONE:
@@ -1538,6 +1591,7 @@
 		int allow_filter_value;
 		int allow_ref_in_want;
 		int allow_sideband_all_value;
+		char *str = NULL;
 
 		strbuf_addstr(value, "shallow");
 
@@ -1559,6 +1613,14 @@
 					   &allow_sideband_all_value) &&
 		     allow_sideband_all_value))
 			strbuf_addstr(value, " sideband-all");
+
+		if (!repo_config_get_string(the_repository,
+					    "uploadpack.blobpackfileuri",
+					    &str) &&
+		    str) {
+			strbuf_addstr(value, " packfile-uris");
+			free(str);
+		}
 	}
 
 	return 1;