[PATCH 2/2] branch: clear target branch configuration before copying or renaming

From

Rubén Justo <rjusto@gmail.com>

Date

Nov 17, 2022, 01:44 UTC

Message-ID

<762c1e8f-fd0c-3b4b-94a0-709d8c9431e4@gmail.com>

In-Reply-To

<f0b2d46c-2e9c-2630-2870-8ed550dd1606@gmail.com>

There are two problems with -m (rename) and -c (copy) branch operations.

 1. If we force-rename or force-copy a branch to overwrite another
 branch that already has configuration, the resultant branch ends up
 with the source configuration (if any) mixed with the configuration for
 the overwritten branch.

	$ git branch upstream
	$ git branch -t foo upstream  # foo has tracking configuration
	$ git branch bar              # bar has not
	$ git branch -M bar foo       # force-rename bar to foo
	$ git config branch.foo.merge # must return clear
	refs/heads/upstream

 2. If we repeatedly force-copy a branch to the same name, the branch
 configuration is repeatedly copied each time.

	$ git branch upstream
	$ git branch -t foo upstream  # foo has tracking configuration
	$ git branch -c foo bar       # bar is a copy of foo
	$ git branch -C foo bar       # again
	$ git branch -C foo bar       # ..
	$ git config --get-all branch.bar.merge # must return one value
	refs/heads/upstream
	refs/heads/upstream
	refs/heads/upstream

Signed-off-by: Rubén Justo <rjusto@gmail.com>
---
 builtin/branch.c  | 17 +++++++++++------
 t/t3200-branch.sh | 19 +++++++++++++++++++
 2 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/builtin/branch.c b/builtin/branch.c
index a35e174aae..14664f0278 100644
--- a/builtin/branch.c
+++ b/builtin/branch.c
@@ -583,12 +583,17 @@ static void copy_or_rename_branch(const char *oldname, const char *newname, int
 
 	strbuf_release(&logmsg);
 
-	strbuf_addf(&oldsection, "branch.%s", interpreted_oldname);
-	strbuf_addf(&newsection, "branch.%s", interpreted_newname);
-	if (!copy && git_config_rename_section(oldsection.buf, newsection.buf) < 0)
-		die(_("Branch is renamed, but update of config-file failed"));
-	if (copy && strcmp(interpreted_oldname, interpreted_newname) && git_config_copy_section(oldsection.buf, newsection.buf) < 0)
-		die(_("Branch is copied, but update of config-file failed"));
+	if (strcmp(interpreted_oldname, interpreted_newname)) {
+		strbuf_addf(&oldsection, "branch.%s", interpreted_oldname);
+		strbuf_addf(&newsection, "branch.%s", interpreted_newname);
+
+		delete_branch_config(interpreted_newname);
+
+		if (!copy && git_config_rename_section(oldsection.buf, newsection.buf) < 0)
+			die(_("Branch is renamed, but update of config-file failed"));
+		if (copy && git_config_copy_section(oldsection.buf, newsection.buf) < 0)
+			die(_("Branch is copied, but update of config-file failed"));
+	}
 	strbuf_release(&oldref);
 	strbuf_release(&newref);
 	strbuf_release(&oldsection);
diff --git a/t/t3200-branch.sh b/t/t3200-branch.sh
index 7f605f865b..c3b3d11c28 100755
--- a/t/t3200-branch.sh
+++ b/t/t3200-branch.sh
@@ -218,6 +218,25 @@ test_expect_success 'git branch -M should leave orphaned HEAD alone' '
 	)
 '
 
+test_expect_success 'git branch -M inherites clean tracking setup' '
+	test_when_finished git branch -D moved &&
+	git branch -t main-tracked main &&
+	git branch non-tracked &&
+	git branch -M main-tracked moved &&
+	git branch --unset-upstream moved &&
+	git branch -M non-tracked moved &&
+	test_must_fail git branch --unset-upstream moved
+'
+
+test_expect_success 'git branch -C inherites clean tracking setup' '
+	test_when_finished git branch -D copiable copied &&
+	git branch -t copiable main &&
+	git branch -C copiable copied &&
+	git branch --unset-upstream copied &&
+	git branch -C copied copiable &&
+	test_must_fail git branch --unset-upstream copiable
+'
+
 test_expect_success 'resulting reflog can be shown by log -g' '
 	oid=$(git rev-parse HEAD) &&
 	cat >expect <<-EOF &&

-- 
2.36.1