Fixed update_tips callback called for failed pushed references

The current implementation does not set 'fire_callback' back to 0 for failed updates so the callback still fires.

Instead of adding yet another condition check to set 'fire_callback' to 0 if needed, considering this function should be a no-op for failed updates anyway, the best fix is to simplify its logic to check upfront if the update is a failed one.

src/push.c

@@ -180,6 +180,10 @@ int git_push_update_tips(git_push *push)
 	git_vector_foreach(&push->status, i, status) {
 		int fire_callback = 1;
 
+		/* Skip unsuccessful updates which have non-empty messages */
+		if (status->msg)
+			continue;
+
 		/* Find the corresponding remote ref */
 		fetch_spec = git_remote__matching_refspec(push->remote, status->ref);
 		if (!fetch_spec)
@@ -198,8 +202,6 @@ int git_push_update_tips(git_push *push)
 		if (j == push->specs.length)
 			continue;
 
-		/* If this ref update was successful (ok, not ng), it will have an empty message */
-		if (status->msg == NULL) {
 		/* Update the remote ref */
 		if (git_oid_iszero(&push_spec->loid)) {
 			error = git_reference_lookup(&remote_ref, push->remote->repo, git_buf_cstr(&remote_ref_name));
@@ -213,7 +215,6 @@ int git_push_update_tips(git_push *push)
 						git_buf_cstr(&remote_ref_name), &push_spec->loid, 1,
 						"update by push");
 		}
-		}
 
 		if (error < 0) {
 			if (error != GIT_ENOTFOUND)