Erroneous SET STATEMENT produces two identical errors

MariaDB [test]> set statement non_existing=1 for select 1;

ERROR 1193 (HY000): Unknown system variable 'non_existing'

MariaDB [test]> show errors;

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

| Level | Code | Message                                |

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

| Error | 1193 | Unknown system variable 'non_existing' |

| Error | 1193 | Unknown system variable 'non_existing' |

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

2 rows in set (0.00 sec)

MariaDB [test]> select @@error_count;

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

| @@error_count |

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

|             2 |

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

1 row in set (0.00 sec)

commit e64f5d8f758bcc1a8856ba9fba01780533f80747

Author: Oleksandr Byelkin <sanja@mariadb.com>

Date:   Sun Oct 26 16:27:54 2014 +0100

    Fixed test suite global variable saving