SET STATEMENT default_week_format = .. has no effect

MariaDB [test]> SELECT @@default_week_format;

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

| @@default_week_format |

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

|                     0 |

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

1 row in set (0.00 sec)

MariaDB [test]> SELECT WEEK('2000-01-01');

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

| WEEK('2000-01-01') |

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

|                  0 |

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

1 row in set (0.00 sec)

MariaDB [test]> SELECT WEEK('2000-01-01',2);

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

| WEEK('2000-01-01',2) |

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

|                   52 |

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

1 row in set (0.00 sec)

MariaDB [test]> SET STATEMENT default_week_format = 2 FOR SELECT WEEK('2000-01-01');

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

| WEEK('2000-01-01') |

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

|                  0 |

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

1 row in set (0.01 sec)

MariaDB [test]> SET default_week_format = 2;

Query OK, 0 rows affected (0.00 sec)

MariaDB [test]> SELECT WEEK('2000-01-01');

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

| WEEK('2000-01-01') |

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

|                 52 |

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

1 row in set (0.00 sec)