SET STATEMENT old_passwords has no effect

MariaDB [test]> set statement OLD_PASSWORDS = 0 for select password('test');

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

| password('test')                          |

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

| *94BDCEBE19083CE2A1F959FD02F964C7AF4CFC29 |

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

1 row in set (0.00 sec)

MariaDB [test]> set statement OLD_PASSWORDS = 1 for select password('test');

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

| password('test')                          |

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

| *94BDCEBE19083CE2A1F959FD02F964C7AF4CFC29 |

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

1 row in set (0.00 sec)

MariaDB [test]> set  old_passwords = 1;

Query OK, 0 rows affected (0.00 sec)

MariaDB [test]>  select password('test');

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

| password('test') |

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

| 378b243e220ca493 |

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

1 row in set (0.00 sec)