Comment 6 for bug 825075

The following query also produces wrong result:

SELECT b, min(a) FROM t1 WHERE a = 7 OR b = 'z' GROUP BY b;
+------+--------+
| b | min(a) |
+------+--------+
| f | 7 |
+------+--------+

While the correct result is:

+------+--------+
| b | min(a) |
+------+--------+
| d | 7 |
| f | 7 |
+------+--------+