Fix review request webhook bug (#35339) (#35723)

Frontport #35339
Fix #35327

services/pull/comment.go

@@ -69,6 +69,10 @@ func CreatePushPullComment(ctx context.Context, pusher *user_model.User, pr *iss
 		if err != nil {
 			return nil, err
 		}
+		// It maybe an empty pull request. Only non-empty pull request need to create push comment
+		if len(data.CommitIDs) == 0 {
+			return nil, nil
+		}
 	}
 
 	dataJSON, err := json.Marshal(data)