CID#1028072 leak undo in corner case

Change-Id: If2371a25c9030c13617df692e82729090280d8f0

sd/source/ui/view/sdview.cxx

@@ -1408,6 +1408,8 @@ void View::ChangeMarkedObjectsBulletsNumbering(
         pSdrModel->AddUndo(pUndoGroup);
         pSdrModel->EndUndo();
     }
+    else
+        delete pUndoGroup;
 
     delete pOutliner;
     delete pOutlinerView;