Codechange: Use a dedicated variable for disaster vehicle action state. (#10798)

src/saveload/oldloader_sl.cpp

@@ -1347,6 +1347,10 @@ bool LoadOldVehicle(LoadgameState *ls, int num)
 		}
 		v->current_order.AssignOrder(UnpackOldOrder(_old_order));
 
+		if (v->type == VEH_DISASTER) {
+			DisasterVehicle::From(v)->state = UnpackOldOrder(_old_order).GetDestination();
+		}
+
 		v->next = (Vehicle *)(size_t)_old_next_ptr;
 
 		if (_cargo_count != 0 && CargoPacket::CanAllocateItem()) {