sign up discards "role" if you use single sign on

[williamstein]

The current sign up page has a new "Select at least one role:" selector:

However, there's a MAJOR bug in that if after selecting roles you click on a single sign on box, then the roles are just completely discarded.

[haraldschilly]

Maybe the selection can be temporarily stored in a cookie and picked up and deleted when the callback happens. That's at least my first idea.