enables the button "Update task end" in the subcontract pop-up,

when the deadline is empty.

FEA: ItEr76S21UpdateEndDateToCustomer

libreplan-webapp/src/main/java/org/libreplan/web/planner/order/SubcontractController.java

@@ -329,6 +329,7 @@ public class SubcontractController extends GenericForwardComposer {
                     if (endDateTask != null) {
                         return (newEndDate.compareTo(endDateTask) != 0);
                     }
+                    return true;
                 }
             }
             return false;