Owner set to null

src/engine/workthreads/DestroyCityThread.java

@@ -143,6 +143,8 @@ public class DestroyCityThread implements Runnable {
                 city.realm = null;
             }
 
+            city.getTOL().setOwner(null);
+
             // It's now safe to delete the city zone from the database
             // which will cause a cascade delete of everything else