branch: do not rename a branch under bisect or rebase

The branch name in that case could be saved in rebase's head_name or
bisect's BISECT_START files. Ideally we should try to update them as
well. But it's trickier (*). Let's play safe and see if the user
complains about inconveniences before doing that.

(*) If we do it, bisect and rebase need to provide an API to rename
branches. We can't do it in worktree.c or builtin/branch.c because
when other people change rebase/bisect code, they may not be aware of
this code and accidentally break it (e.g. rename the branch file, or
refer to the branch in new files). It's a lot more work.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/t/t2025-worktree-add.sh b/t/t2025-worktree-add.sh
index 8f53944..3a22fc5 100755
--- a/t/t2025-worktree-add.sh
+++ b/t/t2025-worktree-add.sh
@@ -254,6 +254,10 @@ test_expect_success 'not allow to delete a branch under rebase' '
 	)
 '
 
+test_expect_success 'rename a branch under rebase not allowed' '
+	test_must_fail git branch -M under-rebase rebase-with-new-name
+'
+
 test_expect_success 'check out from current worktree branch ok' '
 	(
 		cd under-rebase &&
@@ -276,4 +280,8 @@ test_expect_success 'checkout a branch under bisect' '
 	)
 '
 
+test_expect_success 'rename a branch under bisect not allowed' '
+	test_must_fail git branch -M under-bisect bisect-with-new-name
+'
+
 test_done