Concatenation error leads to typo in the warning message

MariaDB [test]> set session_track_system_variables='foo';

Query OK, 0 rows affected, 1 warning (0.000 sec)

MariaDB [test]> show warnings;

+---------+------+--------------------------------------------------------+

| Level   | Code | Message                                                |

+---------+------+--------------------------------------------------------+

| Warning | 1231 | foo is not a valid system variable and willbe ignored. |

+---------+------+--------------------------------------------------------+

1 row in set (0.001 sec)