set_worktree_head_symref(): fix error message

Emit an informative error when failed to hold lock of HEAD.

2233066e (refs: add a new function set_worktree_head_symref,
2016-03-27) added set_worktree_head_symref(), but this is missing a
call to unable_to_lock_message() after hold_lock_file_for_update()
fails, so it emits an empty error message:

  % git branch -m oldname newname
  error:
  error: HEAD of working tree /path/to/wt is not updated
  fatal: Branch renamed to newname, but HEAD is not updated!

Thanks to Eric Sunshine for pointing this out.

Signed-off-by: Kazuki Yamaguchi <k@rhe.jp>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/refs/files-backend.c b/refs/files-backend.c
index ec237efec35d812b8b5be8fb0f6a2988343cde1a..ea78ce9d90f0bb02fcd471c1c113e22053a3ba94 100644 (file)
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -2898,7 +2898,6 @@ int set_worktree_head_symref(const char *gitdir, const char *target)
 {
        static struct lock_file head_lock;
        struct ref_lock *lock;
-       struct strbuf err = STRBUF_INIT;
        struct strbuf head_path = STRBUF_INIT;
        const char *head_rel;
        int ret;
@@ -2906,6 +2905,8 @@ int set_worktree_head_symref(const char *gitdir, const char *target)
        strbuf_addf(&head_path, "%s/HEAD", absolute_path(gitdir));
        if (hold_lock_file_for_update(&head_lock, head_path.buf,
                                      LOCK_NO_DEREF) < 0) {
+               struct strbuf err = STRBUF_INIT;
+               unable_to_lock_message(head_path.buf, errno, &err);
                error("%s", err.buf);
                strbuf_release(&err);
                strbuf_release(&head_path);