wp-db::escape doesn't properly handle objects

[prettyboymp]

The wp_insert_user and wp_update_user functions call get_userdata() which pulls all the usermeta. If any usermeta is stored as a serialized object they are converted to their class, however, the wp-db escape function doesn't properly convert them back to serialized objects before trying to escape them, throwing fatal errors.

[prettyboymp]

sorry, late night, should have searched first. Duplicate of #9640