$auth->assign save N; instead of NULL in field "data"

when I assign an auth_item to a user on his assignment in the field data i find N; instead of NULL.

This thread (http://www.yiiframew…41.msg7706.html) discussed about this issue

I’m also experiencing this problem.

Above link is broken. I’ve been trying to find the correct thread but I cannot find it.

bump

NULL is serialized to N; in php.