xul extension should not show "clear site exception" when monkeysphere state is NOTVALID (or when cache is cleared)
try visiting an https site which doesn't validate via X.509, and which doesn't validate via the monkeysphere.
right-click the monkey with the red slash -- it shouldn't have the "clear site exception" option listed.
This is should probably also be the case if the site's exception has already been cleared.
(from redmine: created on 2010-03-12, closed on 2010-04-25)