message: core: add note about wrong sequence number
  If we pack a message and don't actually send it, we increase the
  sequence number. This will mess with message delivery stats.
diff: @@ -286,6 +286,7 @@ void MAVLinkMissionTransfer::UploadWorkItem::process_mission_request(
  mavlink_mission_request_t request;
  mavlink_msg_mission_request_decode(&request_message, &request);
  + // FIXME: this will mess with the sequence number.
  mavlink_message_t request_int_message;
  mavlink_msg_mission_request_int_pack(
  request_message.sysid,
  