[PATCH] sequencer: don't clobber HEAD ref name in worktree lookup

[Andy Koppe <andy.koppe@gmail.com>]

add_decorations_to_list() skips the branch that HEAD points to, because
the rebase updates it anyway, as per aa37f3e1d89 (sequencer: ignore HEAD
ref under --update-refs, 2022-07-19).

However, it keeps the name of that branch in the static buffer returned
by refs_resolve_ref_unsafe(). If another branch on the same commit is
checked out in a different worktree, branch_checked_out() overwrites
that buffer. If the current branch comes after the other branch in the
list of decorations, it gets a "checked out" comment in the todo list
instead of being skipped, and the branch whose name ended up in the
buffer is skipped in its place.

Decorations are processed in reverse alphabetical order, so this depends
on the branch names. The test added in 94304b9f48e (sequencer: comment
checked-out branch properly, 2024-11-25) happens to trigger the problem
and expects its result.

Fix it by using refs_resolve_refdup(), correct that test's expectation,
and add a test with checked-out branches sorting both before and after
the current branch.

Signed-off-by: Andy Koppe <andy.koppe@gmail.com>
---
 sequencer.c       | 11 ++++++-----
 t/t3400-rebase.sh | 21 ++++++++++++++++++++-
 2 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index 6dae43e4db..c672b6e127 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -6577,11 +6577,11 @@ static int add_decorations_to_list(const struct commit *commit,
 				   struct todo_add_branch_context *ctx)
 {
 	const struct name_decoration *decoration = get_name_decoration(&commit->object);
-	const char *head_ref = refs_resolve_ref_unsafe(get_main_ref_store(the_repository),
-						       "HEAD",
-						       RESOLVE_REF_READING,
-						       NULL,
-						       NULL);
+	char *head_ref = refs_resolve_refdup(get_main_ref_store(the_repository),
+					     "HEAD",
+					     RESOLVE_REF_READING,
+					     NULL,
+					     NULL);
 
 	while (decoration) {
 		struct todo_item *item;
@@ -6633,6 +6633,7 @@ static int add_decorations_to_list(const struct commit *commit,
 		decoration = decoration->next;
 	}
 
+	free(head_ref);
 	return 0;
 }
 
diff --git a/t/t3400-rebase.sh b/t/t3400-rebase.sh
index accaaba4d4..0e7ef33eb1 100755
--- a/t/t3400-rebase.sh
+++ b/t/t3400-rebase.sh
@@ -483,7 +483,26 @@ test_expect_success 'git rebase --update-ref with core.commentChar and branch on
 	GIT_SEQUENCE_EDITOR="cat >actual" git -c core.commentChar=% \
 		 rebase -i --update-refs base &&
 	test_grep "% Ref refs/heads/wt-topic checked out at" actual &&
-	test_grep "% Ref refs/heads/topic2 checked out at" actual
+	test_grep ! "Ref refs/heads/topic2" actual
+'
+
+test_expect_success 'git rebase --update-refs ignores current branch with branches on worktrees' '
+	test_when_finished git branch -D base current a-topic z-topic &&
+	test_when_finished git checkout main &&
+	test_when_finished git worktree remove z-topic &&
+	test_when_finished git worktree remove a-topic &&
+	git checkout -b base main &&
+	git checkout -b current &&
+	test_commit msg4 &&
+	git worktree add a-topic &&
+	git worktree add z-topic &&
+	git checkout base &&
+	test_commit msg5 &&
+	git checkout current &&
+	GIT_SEQUENCE_EDITOR="cat >actual" git rebase -i --update-refs base &&
+	test_grep "# Ref refs/heads/a-topic checked out at" actual &&
+	test_grep "# Ref refs/heads/z-topic checked out at" actual &&
+	test_grep ! "refs/heads/current" actual
 '
 
 test_done
-- 
2.56.0