Comment 5 for bug 869001

As pointed by Philip on IRC: current server produces different EXPLAIN:
+----+-------------+-------+--------+---------------+------+---------+-------+------+----------------------------------------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-------+--------+---------------+------+---------+-------+------+----------------------------------------------------------------+
| 1 | PRIMARY | t2 | system | NULL | NULL | NULL | NULL | 1 | |
| 1 | PRIMARY | t1 | ref | f3 | f3 | 4 | const | 1 | Using index; Start temporary |
| 1 | PRIMARY | t4 | ALL | NULL | NULL | NULL | NULL | 3 | Using join buffer (flat, BNL join) |
| 1 | PRIMARY | t3 | ALL | NULL | NULL | NULL | NULL | 5 | Using where; End temporary; Using join buffer (flat, BNL join) |
+----+-------------+-------+--------+---------------+------+---------+-------+------+----------------------------------------------------------------+