MaxScale Mask Filter incorrectly handles ANSI_QUOTES

mysql> select concat(ssn) from managers;

ERROR 1141 (HY000): The function concat is used in conjunction with a field that should be masked for 'maxuser'@'::ffff:127.0.0.1', access is denied.

mysql> set @@sql_mode = 'ANSI_QUOTES';

Query OK, 0 rows affected (0.00 sec)

mysql> select concat("ssn") from managers;

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

| concat("ssn") |

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

| 111-22-3333   |

| 444-55-6666   |

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

2 rows in set (0.00 sec)