fetch: Check for a "^{}" suffix with suffixcmp()

Otherwise, we will check random bytes for ref names < 3 characters.
Signed-off-by: NAndreas Gruenbacher <agruen@suse.de>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

builtin-fetch.c

@@ -588,7 +588,7 @@ static void find_non_local_tags(struct transport *transport,
 		 * to fetch then we can mark the ref entry in the list
 		 * as one to ignore by setting util to NULL.
 		 */
-		if (!strcmp(ref->name + strlen(ref->name) - 3, "^{}")) {
+		if (!suffixcmp(ref->name, "^{}")) {
 			if (item && !has_sha1_file(ref->old_sha1) &&
 			    !will_fetch(head, ref->old_sha1) &&
 			    !has_sha1_file(item->util) &&