diff --git a/t/t3427-rebase-subtree.sh b/t/t3427-rebase-subtree.sh
index 79e43a3..2a7d958 100755
--- a/t/t3427-rebase-subtree.sh
+++ b/t/t3427-rebase-subtree.sh
@@ -15,12 +15,12 @@
 # this test script tries to document them.  First, the following commit history
 # is generated (the onelines are shown, time flows from left to right):
 #
-# master1 - master2 - master3
+# topic_1 - topic_2 - topic_3
 #                             \
-# README ---------------------- Add subproject master - master4 - files_subtree/master5
+# README ---------------------- Add subproject master - topic_4 - files_subtree/topic_5
 #
 # Where the merge moves the files master[123].t into the subdirectory
-# files_subtree/ and master4 as well as files_subtree/master5 add files to that
+# files_subtree/ and topic_4 as well as files_subtree/topic_5 add files to that
 # directory directly.
 #
 # Then, in subsequent test cases, `git filter-branch` is used to distill just
@@ -28,11 +28,11 @@
 # an empty commit is added on top. The pre-rebase commit history looks like
 # this:
 #
-# Add subproject master - master4 - files_subtree/master5 - Empty commit
+# Add subproject master - topic_4 - files_subtree/topic_5 - Empty commit
 #
-# where the root commit adds three files: master1.t, master2.t and master3.t.
+# where the root commit adds three files: topic_1.t, topic_2.t and topic_3.t.
 #
-# This commit history is then rebased onto `master3` with the
+# This commit history is then rebased onto `topic_3` with the
 # `-Xsubtree=files_subtree` option in three different ways:
 #
 # 1. using `--preserve-merges`
@@ -43,9 +43,9 @@
 	test_commit README &&
 
 	git init files &&
-	test_commit -C files master1 &&
-	test_commit -C files master2 &&
-	test_commit -C files master3 &&
+	test_commit -C files topic_1 &&
+	test_commit -C files topic_2 &&
+	test_commit -C files topic_3 &&
 
 	: perform subtree merge into files_subtree/ &&
 	git fetch files refs/heads/master:refs/heads/files-master &&
@@ -55,8 +55,8 @@
 	git commit -m "Add subproject master" &&
 
 	: add two extra commits to rebase &&
-	test_commit -C files_subtree master4 &&
-	test_commit files_subtree/master5 &&
+	test_commit -C files_subtree topic_4 &&
+	test_commit files_subtree/topic_5 &&
 
 	git checkout -b to-rebase &&
 	git fast-export --no-data HEAD -- files_subtree/ |
@@ -66,22 +66,22 @@
 	git commit -m "Empty commit" --allow-empty
 '
 
-# FAILURE: Does not preserve master4.
+# FAILURE: Does not preserve topic_4.
 test_expect_failure REBASE_P 'Rebase -Xsubtree --preserve-merges --onto commit' '
 	reset_rebase &&
 	git checkout -b rebase-preserve-merges to-rebase &&
 	git rebase -Xsubtree=files_subtree --preserve-merges --onto files-master master &&
-	verbose test "$(commit_message HEAD~)" = "master4" &&
-	verbose test "$(commit_message HEAD)" = "files_subtree/master5"
+	verbose test "$(commit_message HEAD~)" = "topic_4" &&
+	verbose test "$(commit_message HEAD)" = "files_subtree/topic_5"
 '
 
-# FAILURE: Does not preserve master4.
+# FAILURE: Does not preserve topic_4.
 test_expect_failure REBASE_P 'Rebase -Xsubtree --keep-empty --preserve-merges --onto commit' '
 	reset_rebase &&
 	git checkout -b rebase-keep-empty to-rebase &&
 	git rebase -Xsubtree=files_subtree --keep-empty --preserve-merges --onto files-master master &&
-	verbose test "$(commit_message HEAD~2)" = "master4" &&
-	verbose test "$(commit_message HEAD~)" = "files_subtree/master5" &&
+	verbose test "$(commit_message HEAD~2)" = "topic_4" &&
+	verbose test "$(commit_message HEAD~)" = "files_subtree/topic_5" &&
 	verbose test "$(commit_message HEAD)" = "Empty commit"
 '
 
@@ -91,8 +91,8 @@
 	test_must_fail git rebase -Xsubtree=files_subtree --empty=ask --onto files-master master &&
 	: first pick results in no changes &&
 	git rebase --skip &&
-	verbose test "$(commit_message HEAD~2)" = "master4" &&
-	verbose test "$(commit_message HEAD~)" = "files_subtree/master5" &&
+	verbose test "$(commit_message HEAD~2)" = "topic_4" &&
+	verbose test "$(commit_message HEAD~)" = "files_subtree/topic_5" &&
 	verbose test "$(commit_message HEAD)" = "Empty commit"
 '
 
@@ -102,8 +102,8 @@
 	test_must_fail git rebase -Xsubtree=files_subtree --empty=ask --rebase-merges --onto files-master --root &&
 	: first pick results in no changes &&
 	git rebase --skip &&
-	verbose test "$(commit_message HEAD~2)" = "master4" &&
-	verbose test "$(commit_message HEAD~)" = "files_subtree/master5" &&
+	verbose test "$(commit_message HEAD~2)" = "topic_4" &&
+	verbose test "$(commit_message HEAD~)" = "files_subtree/topic_5" &&
 	verbose test "$(commit_message HEAD)" = "Empty commit"
 '
 
diff --git a/t/t4150-am.sh b/t/t4150-am.sh
index 1da8ab1..3ecbef6 100755
--- a/t/t4150-am.sh
+++ b/t/t4150-am.sh
@@ -465,7 +465,7 @@
 test_expect_success 'am --signoff adds Signed-off-by: line' '
 	rm -fr .git/rebase-apply &&
 	git reset --hard &&
-	git checkout -b master2 first &&
+	git checkout -b topic_2 first &&
 	git am --signoff <patch2 &&
 	{
 		printf "third\n\nSigned-off-by: %s <%s>\n\n" \
@@ -479,7 +479,7 @@
 '
 
 test_expect_success 'am stays in branch' '
-	echo refs/heads/master2 >expected &&
+	echo refs/heads/topic_2 >expected &&
 	git symbolic-ref HEAD >actual &&
 	test_cmp expected actual
 '
@@ -540,7 +540,7 @@
 	git reset --hard HEAD^ &&
 	git am <patch4 &&
 	git rev-parse HEAD >expected &&
-	git rev-parse master2 >actual &&
+	git rev-parse topic_2 >actual &&
 	test_cmp expected actual
 '
 
@@ -567,7 +567,7 @@
 test_expect_success 'setup am -3' '
 	rm -fr .git/rebase-apply &&
 	git reset --hard &&
-	git checkout -b base3way master2 &&
+	git checkout -b base3way topic_2 &&
 	sed -n -e "3,\$p" msg >file &&
 	head -n 9 msg >>file &&
 	git add file &&
diff --git a/t/t5515-fetch-merge-logic.sh b/t/t5515-fetch-merge-logic.sh
index 9d6a46f..70a9d2d 100755
--- a/t/t5515-fetch-merge-logic.sh
+++ b/t/t5515-fetch-merge-logic.sh
@@ -15,7 +15,7 @@
 
 build_script () {
 	script="$1" &&
-	for i in one three_file master master2 one_tree three two two2 three2
+	for i in one three_file master topic_2 one_tree three two two2 three2
 	do
 		echo "s/$(test_oid --hash=sha1 "$i")/$(test_oid "$i")/g" >>"$script"
 	done
@@ -52,8 +52,8 @@
 	two sha1:525b7fb068d59950d185a8779dc957c77eed73ba
 	two sha256:3b21de3440cd38c2a9e9b464adb923f7054949ed4c918e1a0ac4c95cd52774db
 
-	master2 sha1:754b754407bf032e9a2f9d5a9ad05ca79a6b228f
-	master2 sha256:6c7abaea8a6d8ef4d89877e68462758dc6774690fbbbb0e6d7dd57415c9abde0
+	topic_2 sha1:754b754407bf032e9a2f9d5a9ad05ca79a6b228f
+	topic_2 sha256:6c7abaea8a6d8ef4d89877e68462758dc6774690fbbbb0e6d7dd57415c9abde0
 
 	two2 sha1:6134ee8f857693b96ff1cc98d3e2fd62b199e5a8
 	two2 sha256:87a2d3ee29c83a3dc7afd41c0606b11f67603120b910a7be7840accdc18344d4
diff --git a/t/t5523-push-upstream.sh b/t/t5523-push-upstream.sh
index c0df81a..e47b5db 100755
--- a/t/t5523-push-upstream.sh
+++ b/t/t5523-push-upstream.sh
@@ -41,20 +41,20 @@
 	check_config master upstream refs/heads/other
 '
 
-test_expect_success 'push -u master2:master2' '
-	git branch master2 &&
-	git push -u upstream master2:master2 &&
-	check_config master2 upstream refs/heads/master2
+test_expect_success 'push -u topic_2:topic_2' '
+	git branch topic_2 &&
+	git push -u upstream topic_2:topic_2 &&
+	check_config topic_2 upstream refs/heads/topic_2
 '
 
-test_expect_success 'push -u master2:other2' '
-	git push -u upstream master2:other2 &&
-	check_config master2 upstream refs/heads/other2
+test_expect_success 'push -u topic_2:other2' '
+	git push -u upstream topic_2:other2 &&
+	check_config topic_2 upstream refs/heads/other2
 '
 
-test_expect_success 'push -u :master2' '
-	git push -u upstream :master2 &&
-	check_config master2 upstream refs/heads/other2
+test_expect_success 'push -u :topic_2' '
+	git push -u upstream :topic_2 &&
+	check_config topic_2 upstream refs/heads/other2
 '
 
 test_expect_success 'push -u --all' '
diff --git a/t/t6018-rev-list-glob.sh b/t/t6018-rev-list-glob.sh
index b31ff7e..fe2f3ce 100755
--- a/t/t6018-rev-list-glob.sh
+++ b/t/t6018-rev-list-glob.sh
@@ -32,11 +32,11 @@
 	git checkout -b someref master &&
 	commit some &&
 	git checkout master &&
-	commit master2 &&
+	commit topic_2 &&
 	git tag foo/bar master &&
-	commit master3 &&
+	commit topic_3 &&
 	git update-ref refs/remotes/foo/baz master &&
-	commit master4 &&
+	commit topic_4 &&
 	git update-ref refs/remotes/upstream/one subspace/one &&
 	git update-ref refs/remotes/upstream/two subspace/two &&
 	git update-ref refs/remotes/upstream/x subspace-x &&
diff --git a/t/t6040-tracking-info.sh b/t/t6040-tracking-info.sh
index ad1922b..50a934e 100755
--- a/t/t6040-tracking-info.sh
+++ b/t/t6040-tracking-info.sh
@@ -264,25 +264,25 @@
 test_expect_success '--set-upstream-to does not change branch' '
 	git branch from-master master &&
 	git branch --set-upstream-to master from-master &&
-	git branch from-master2 master &&
-	test_must_fail git config branch.from-master2.merge > actual &&
-	git rev-list from-master2 &&
-	git update-ref refs/heads/from-master2 from-master2^ &&
-	git rev-parse from-master2 >expect2 &&
-	git branch --set-upstream-to master from-master2 &&
+	git branch from-topic_2 master &&
+	test_must_fail git config branch.from-topic_2.merge > actual &&
+	git rev-list from-topic_2 &&
+	git update-ref refs/heads/from-topic_2 from-topic_2^ &&
+	git rev-parse from-topic_2 >expect2 &&
+	git branch --set-upstream-to master from-topic_2 &&
 	git config branch.from-master.merge > actual &&
-	git rev-parse from-master2 >actual2 &&
+	git rev-parse from-topic_2 >actual2 &&
 	grep -q "^refs/heads/master$" actual &&
 	cmp expect2 actual2
 '
 
 test_expect_success '--set-upstream-to @{-1}' '
 	git checkout follower &&
-	git checkout from-master2 &&
-	git config branch.from-master2.merge > expect2 &&
+	git checkout from-topic_2 &&
+	git config branch.from-topic_2.merge > expect2 &&
 	git branch --set-upstream-to @{-1} from-master &&
 	git config branch.from-master.merge > actual &&
-	git config branch.from-master2.merge > actual2 &&
+	git config branch.from-topic_2.merge > actual2 &&
 	git branch --set-upstream-to follower from-master &&
 	git config branch.from-master.merge > expect &&
 	test_cmp expect2 actual2 &&
diff --git a/t/t6409-merge-subtree.sh b/t/t6409-merge-subtree.sh
index 793f0c8..1a0d0e2 100755
--- a/t/t6409-merge-subtree.sh
+++ b/t/t6409-merge-subtree.sh
@@ -94,10 +94,10 @@
 	echo git-gui2 > git-gui.sh &&
 	o3=$(git hash-object git-gui.sh) &&
 	git add git-gui.sh &&
-	git checkout -b master2 &&
+	git checkout -b topic_2 &&
 	git commit -m "update git-gui" &&
 	cd ../git &&
-	git pull -s subtree gui master2 &&
+	git pull -s subtree gui topic_2 &&
 	git ls-files -s >actual &&
 	(
 		echo "100644 $o3 0	git-gui/git-gui.sh" &&
@@ -109,7 +109,7 @@
 test_expect_success 'initial ambiguous subtree' '
 	cd ../git &&
 	git reset --hard master &&
-	git checkout -b master2 &&
+	git checkout -b topic_2 &&
 	git merge -s ours --no-commit gui/master &&
 	git read-tree --prefix=git-gui2/ -u gui/master &&
 	git commit -m "Merge git-gui2 as our subdirectory" &&
@@ -125,8 +125,8 @@
 
 test_expect_success 'merge using explicit' '
 	cd ../git &&
-	git reset --hard master2 &&
-	git pull -Xsubtree=git-gui gui master2 &&
+	git reset --hard topic_2 &&
+	git pull -Xsubtree=git-gui gui topic_2 &&
 	git ls-files -s >actual &&
 	(
 		echo "100644 $o3 0	git-gui/git-gui.sh" &&
@@ -138,8 +138,8 @@
 
 test_expect_success 'merge2 using explicit' '
 	cd ../git &&
-	git reset --hard master2 &&
-	git pull -Xsubtree=git-gui2 gui master2 &&
+	git reset --hard topic_2 &&
+	git pull -Xsubtree=git-gui2 gui topic_2 &&
 	git ls-files -s >actual &&
 	(
 		echo "100644 $o1 0	git-gui/git-gui.sh" &&