HAVING does not reject the result of aggregation

[Igor Babaev]

Using mariadb-5.2 create and populate table 1 with the following commands:

CREATE TABLE t1 (pk INT PRIMARY KEY, a INT);
INSERT INTO t1 VALUES (2,7), (4,7), (6,2), (17,0);

Execute the following queries:
SELECT MIN(t.pk) FROM t1, t1 as t WHERE t1.pk = 1;
SELECT MIN(t.pk) FROM t1, t1 as t WHERE t1.pk = 1 HAVING MIN(t.pk) < 10;

The first query return the right result while the second query returns a wrong result:

MariaDB [test]> SELECT MIN(t.pk) FROM t1, t1 as t WHERE t1.pk = 1;
+-----------+
| MIN(t.pk) |
+-----------+
| NULL |
+-----------+

MariaDB [test]> SELECT MIN(t.pk) FROM t1, t1 as t WHERE t1.pk = 1 HAVING MIN(t.pk) < 10;
+-----------+
| MIN(t.pk) |
+-----------+
| NULL |
+-----------+