TBTR: Fix template replacement refits having 0 cost

src/tbtr_template_vehicle_func.cpp

@@ -346,18 +346,21 @@ int NumTrainsNeedTemplateReplacement(GroupID g_id, const TemplateVehicle *tv)
 	return count;
 }
 // refit each vehicle in t as is in tv, assume t and tv contain the same types of vehicles
-void CmdRefitTrainFromTemplate(Train *t, TemplateVehicle *tv, DoCommandFlag flags)
+CommandCost CmdRefitTrainFromTemplate(Train *t, TemplateVehicle *tv, DoCommandFlag flags)
 {
+	CommandCost cost(t->GetExpenseType(false));
+
 	while (t && tv) {
 		// refit t as tv
 		uint32 cb = GetCmdRefitVeh(t);
 
-		DoCommand(t->tile, t->index, tv->cargo_type | tv->cargo_subtype << 8 | (1 << 16) | (1 << 31), flags, cb);
+		cost.AddCost(DoCommand(t->tile, t->index, tv->cargo_type | tv->cargo_subtype << 8 | (1 << 16) | (1 << 31), flags, cb));
 
 		// next
 		t = t->GetNextUnit();
 		tv = tv->GetNextUnit();
 	}
+	return cost;
 }
 
 /** using cmdtemplatereplacevehicle as test-function (i.e. with flag DC_NONE) is not a good idea as that function relies on

src/tbtr_template_vehicle_func.h

@@ -46,7 +46,7 @@ int NumTrainsNeedTemplateReplacement(GroupID, const TemplateVehicle*);
 
 CommandCost TestBuyAllTemplateVehiclesInChain(TemplateVehicle *tv, TileIndex tile);
 
-void CmdRefitTrainFromTemplate(Train *t, TemplateVehicle *tv, DoCommandFlag);
+CommandCost CmdRefitTrainFromTemplate(Train *t, TemplateVehicle *tv, DoCommandFlag);
 void BreakUpRemainders(Train *t);
 
 bool TemplateVehicleContainsEngineOfRailtype(const TemplateVehicle*, RailType);

src/train_cmd.cpp

@@ -5659,7 +5659,7 @@ CommandCost CmdTemplateReplaceVehicle(TileIndex tile, DoCommandFlag flags, uint3
 
 	// refit, only if the template option is set so
 	if (use_refit && (need_refit || need_replacement)) {
-		CmdRefitTrainFromTemplate(new_chain, tv, flags);
+		buy.AddCost(CmdRefitTrainFromTemplate(new_chain, tv, flags));
 	}
 
 	if (new_chain && remainder_chain) {