You can click on the Google or Yahoo buttons to sign-in with these identity providers,
or you just type your identity uri and click on the little login button.
attached test cube reproduces the bug.
not related to inheritance, but clearly a bug. Demonstrated and fixed by 03121ca1f85e in stable branch
Ticket #522329 - latest update on 2010/02/26, created on 2009/11/13 by Florent Cayré