Apply for role doesn't use hook_user properly

When using the hook_user()'s insert or update operations the module should save its custom additions to the user object into the database and set the saved fields to NULL in $edit. If it is not done such additions get serialized and saved into 'data' column.

This happens with $form['apply_for_role']['rid'] element. It is saved into {users} table and sticks there forever. Also it is added every time to a $user object when it is loaded.