(svn r11928) -Fix (r6393): [autoreplace] autoreplace could refit train engines to the wrong cargo type if the old engine had no cargo capacity and the new one had

Now autoreplace will always look at the wagons to figure out what to replace to (as originally intended)

src/autoreplace_cmd.cpp

@@ -93,7 +93,7 @@ static CargoID GetNewCargoTypeForReplace(Vehicle *v, EngineID engine_type)
 
 	if (new_cargo_type == CT_INVALID) return CT_NO_REFIT; // Don't try to refit an engine with no cargo capacity
 
-	if (v->cargo_type == new_cargo_type || CanRefitTo(engine_type, v->cargo_type)) {
+	if (v->cargo_cap != 0 && (v->cargo_type == new_cargo_type || CanRefitTo(engine_type, v->cargo_type))) {
 		if (VerifyAutoreplaceRefitForOrders(v, engine_type)) {
 			return v->cargo_type == new_cargo_type ? (CargoID)CT_NO_REFIT : v->cargo_type;
 		} else {