http-push: free repo->url string

Our repo->url string comes from str_end_url_with_slash(), which always
allocates its output buffer. We should free it before exiting to avoid
triggering the leak-checker.

This can be seen by leak-checking t5540.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

http-push.c

@@ -1972,6 +1972,7 @@ int cmd_main(int argc, const char **argv)
  cleanup:
 	if (info_ref_lock)
 		unlock_remote(info_ref_lock);
+	free(repo->url);
 	free(repo);
 
 	http_cleanup();