Right now, if you access Special:UserRights while logged out (or with an account that doesn't have the right to change other users' rights) you will see an error message.

This is bad. Instead, Special:UserRights should show the user's rights. Only the checkboxes and buttons for changing user's rights should be hidden, but the top part (where a user's explicit and implicit memerbship is listed) should be available to the public.

Observed:

Expected: