Tracerestrict: Add a group membership conditional.

src/group_cmd.cpp

@@ -21,6 +21,7 @@
 #include "company_func.h"
 #include "core/pool_func.hpp"
 #include "order_backup.h"
+#include "tracerestrict.h"
 
 #include "table/strings.h"
 
@@ -341,6 +342,9 @@ CommandCost CmdDeleteGroup(TileIndex tile, DoCommandFlag flags, uint32 p1, uint3
 
 		VehicleType vt = g->vehicle_type;
 
+		/* notify tracerestrict that group is about to be deleted */
+		TraceRestrictRemoveGroupID(g->index);
+
 		/* Delete the Replace Vehicle Windows */
 		DeleteWindowById(WC_REPLACE_VEHICLE, g->vehicle_type);
 		delete g;