* $GIT_DIR points to.
* Return 0 if successful, non-zero otherwise.
* */
-int set_worktree_head_symref(const char *gitdir, const char *target);
+int set_worktree_head_symref(const char *gitdir, const char *target,
+ const char *logmsg);
enum action_on_err {
UPDATE_REFS_MSG_ON_ERR,