Can't Hook class->method() in call_user_func[_array] which class is defined in extension

[hemon]

i created a test:
https://github.com/hemon/phpio/blob/master/test/redis2.php

class(myredis) is a wrapper class for redis, it has a margic method __call() to call real method defined in class(redis);

WHEN:

1. class(redis2) is defined in php script, aop can hook it;
2. class(redis) is defined in phpredis extension, aop CAN'T hook it.