message: net: trying to fix block serialization when sending to older clients
diff: @@ -19,7 +19,8 @@ public:
  {
  CSerializedNetMsg msg;
  msg.command = std::move(sCommand);
  - CVectorWriter{ SER_NETWORK | SER_POSMARKER, nFlags | nVersion, msg.data, 0, std::forward<Args>(args)... };
  + int32_t serModes = nVersion <= OLD_VERSION ? SER_NETWORK : SER_NETWORK | SER_POSMARKER;
  + CVectorWriter{ serModes, nFlags | nVersion, msg.data, 0, std::forward<Args>(args)... };
  return msg;
  }
  