Fix CMSG_CHANGE_SEATS_ON_CONTROLLED_VEHICLE and CMSG_REQUEST_VEHICLE_SWITCH_SEAT handlers

Modified version of Havenard's patch
Closes issue 1452

--HG--
branch : trunk

src/game/MovementHandler.cpp

@@ -589,7 +589,7 @@ void WorldSession::HandleChangeSeatsOnControlledVehicle(WorldPacket &recv_data)
     case CMSG_CHANGE_SEATS_ON_CONTROLLED_VEHICLE:
         {
             uint64 guid;        // current vehicle guid
-            if (!recv_data.readPackGUID(guid) || vehicle_base->GetGUID() != guid)
+            if (!recv_data.readPackGUID(guid))
                 return;
 
             ReadMovementInfo(recv_data, &vehicle_base->m_movementInfo);
@@ -601,6 +601,9 @@ void WorldSession::HandleChangeSeatsOnControlledVehicle(WorldPacket &recv_data)
             int8 seatId;
             recv_data >> seatId;
 
+			if (vehicle_base->GetGUID() != guid)
+				return;
+
             if (!accessory)
                 GetPlayer()->ChangeSeat(-1, seatId > 0); // prev/next
             else if (Unit *vehUnit = Unit::GetUnit(*GetPlayer(), accessory))
@@ -614,13 +617,14 @@ void WorldSession::HandleChangeSeatsOnControlledVehicle(WorldPacket &recv_data)
     case CMSG_REQUEST_VEHICLE_SWITCH_SEAT:
         {
             uint64 guid;        // current vehicle guid
-            if (!recv_data.readPackGUID(guid) || vehicle_base->GetGUID() != guid)
+            if (!recv_data.readPackGUID(guid))
                 return;
 
             int8 seatId;
             recv_data >> seatId;
 
-            GetPlayer()->ChangeSeat(-1, seatId > 0); // prev/next
+			if (vehicle_base->GetGUID() == guid)
+	            GetPlayer()->ChangeSeat(seatId);
         }
         break;
     default: