Members of the group administrators shoud be able to remove the user Administrator from local rights

Steps to reproduce:

1. Create a user and put him in the group "administrators".
2. Create local rights in a specific document for Administrator.
3. Log in with this user.
4. Go to this specific document on default server.
5. Try to remove Administrator from local rights.
   -> You are displayed a message that says: "You can't remove your own rights".