Silence the slow log errors (they won't make it to the client anyway).

  bool result= TRUE;

  bool need_close= FALSE;

  bool need_rnd_end= FALSE;

  Silence_log_table_errors error_handler;

  Open_tables_state open_tables_backup;

  CHARSET_INFO *client_cs= thd->variables.character_set_client;

  bool save_time_zone_used;

  DBUG_ENTER("Log_to_csv_event_handler::log_slow");

  thd->push_internal_handler(& error_handler);

  /*

    CSV uses TIME_to_timestamp() internally if table needs to be repaired

    which will set thd->time_zone_used

  result= FALSE;

err:

  thd->pop_internal_handler();

  if (result)

    sql_print_error("Failed to write to mysql.slow_log");

    sql_print_error("Failed to write to mysql.slow_log: %s",

                    error_handler.message());

  if (need_rnd_end)

  {