(svn r24713) -Fix [FS#5262]: [NewGRF] Tolerate old NewGRFs returning invalid values via CB 11.

src/roadveh_cmd.cpp

@@ -169,13 +169,13 @@ static uint GetRoadVehLength(const RoadVehicle *v)
 	if (e->GetGRF() != NULL && e->GetGRF()->grf_version >= 8) {
 		/* Use callback 36 */
 		veh_len = GetVehicleProperty(v, PROP_ROADVEH_SHORTEN_FACTOR, CALLBACK_FAILED);
+		if (veh_len != CALLBACK_FAILED && veh_len >= VEHICLE_LENGTH) ErrorUnknownCallbackResult(e->GetGRFID(), CBID_VEHICLE_LENGTH, veh_len);
 	} else {
 		/* Use callback 11 */
 		veh_len = GetVehicleCallback(CBID_VEHICLE_LENGTH, 0, 0, v->engine_type, v);
 	}
 	if (veh_len == CALLBACK_FAILED) veh_len = e->u.road.shorten_factor;
 	if (veh_len != 0) {
-		if (veh_len >= VEHICLE_LENGTH) ErrorUnknownCallbackResult(e->GetGRFID(), CBID_VEHICLE_LENGTH, veh_len);
 		length -= Clamp(veh_len, 0, VEHICLE_LENGTH - 1);
 	}
 

src/train_cmd.cpp

@@ -208,13 +208,14 @@ void Train::ConsistChanged(bool same_length)
 		if (e_u->GetGRF() != NULL && e_u->GetGRF()->grf_version >= 8) {
 			/* Use callback 36 */
 			veh_len = GetVehicleProperty(u, PROP_TRAIN_SHORTEN_FACTOR, CALLBACK_FAILED);
+
+			if (veh_len != CALLBACK_FAILED && veh_len >= VEHICLE_LENGTH) {
+				ErrorUnknownCallbackResult(e_u->GetGRFID(), CBID_VEHICLE_LENGTH, veh_len);
+			}
 		} else if (HasBit(e_u->info.callback_mask, CBM_VEHICLE_LENGTH)) {
 			/* Use callback 11 */
 			veh_len = GetVehicleCallback(CBID_VEHICLE_LENGTH, 0, 0, u->engine_type, u);
 		}
-		if (veh_len != CALLBACK_FAILED && veh_len >= VEHICLE_LENGTH) {
-			ErrorUnknownCallbackResult(e_u->GetGRFID(), CBID_VEHICLE_LENGTH, veh_len);
-		}
 		if (veh_len == CALLBACK_FAILED) veh_len = rvi_u->shorten_factor;
 		veh_len = VEHICLE_LENGTH - Clamp(veh_len, 0, VEHICLE_LENGTH - 1);