files-backend: don't rewrite the `packed-refs` file unnecessarily

diff --git a/worktree.h b/worktree.h
index d59ce1fee875800462a1e464592fd9dd01828e17..5ea5e503fbe491a76d3c8ce279b7e281a5d07d3e 100644 (file)
--- a/worktree.h
+++ b/worktree.h
@@ -4,7 +4,7 @@
 struct worktree {
        char *path;
        char *id;
-       char *head_ref;
+       char *head_ref;         /* NULL if HEAD is broken or detached */
        char *lock_reason;      /* internal use */
        unsigned char head_sha1[20];
        int is_detached;
@@ -27,6 +27,11 @@ struct worktree {
  */
 extern struct worktree **get_worktrees(unsigned flags);
 
+/*
+ * Returns 1 if linked worktrees exist, 0 otherwise.
+ */
+extern int submodule_uses_worktrees(const char *path);
+
 /*
  * Return git dir of the worktree. Note that the path may be relative.
  * If wt is NULL, git dir of current worktree is returned.