Bug #6812 Triggers are not activated for INSERT ... SELECT

Description:
I have a BEFORE INSERT trigger, it should increment a variable every time a row is 
inserted in table t. It works okay when I use INSERT ... VALUES. But nothing happens when 
I use INSERT ... SELECT. 
 

How to repeat:
mysql> create table t (s1 int); 
Query OK, 0 rows affected (0.28 sec) 
 
mysql> create trigger t_bi before insert on t for each row set @x = @x + 1; 
Query OK, 0 rows affected (0.00 sec) 
 
mysql> set @x = 0; 
Query OK, 0 rows affected (0.00 sec) 
 
mysql> insert into t values (0); 
Query OK, 1 row affected (0.00 sec) 
 
mysql> select @x; 
+------+ 
| @x   | 
+------+ 
| 1    | 
+------+ 
1 row in set (0.00 sec) 
 
mysql> insert into t select * from t; 
Query OK, 1 row affected (0.00 sec) 
Records: 1  Duplicates: 0  Warnings: 0 
 
mysql> select @x; 
+------+ 
| @x   | 
+------+ 
| 1    | 
+------+ 
1 row in set (0.00 sec)

Fixed in 5.0.7

Noted in 5.0.7 changelog.