refs: lock symref that is to be deleted, not its target

When delete_ref is called on a symref then it locks its target and then
either deletes the target or the symref, depending on whether the flag
REF_NODEREF was set in the parameter delopt.

Instead, simply pass the flag to lock_ref_sha1_basic, which will then
either lock the target or the symref, and delete the locked ref.

This reimplements part of eca35a25 (Fix git branch -m for symrefs.).

Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

refs.c

@@ -1753,25 +1753,17 @@ int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
 	struct ref_lock *lock;
 	int err, i = 0, ret = 0, flag = 0;
 
-	lock = lock_ref_sha1_basic(refname, sha1, 0, &flag);
+	lock = lock_ref_sha1_basic(refname, sha1, delopt, &flag);
 	if (!lock)
 		return 1;
 	if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
 		/* loose */
-		const char *path;
-
-		if (!(delopt & REF_NODEREF)) {
 		i = strlen(lock->lk->filename) - 5; /* .lock */
 		lock->lk->filename[i] = 0;
-			path = lock->lk->filename;
-		} else {
-			path = git_path("%s", refname);
-		}
-		err = unlink_or_warn(path);
+		err = unlink_or_warn(lock->lk->filename);
 		if (err && errno != ENOENT)
 			ret = 1;
 
-		if (!(delopt & REF_NODEREF))
 		lock->lk->filename[i] = '.';
 	}
 	/* removing the loose one could have resurrected an earlier