Some auth backends do not provide all informations required to correctly
set up a user profile in review board. IMHO a good idea would be adding a
property/method to the auth backend which could specify if the backend
provides fields like email/first name/etc if not the user would be
presented with the same fields as for the "builtin" backend on first login,
except those provided by the specified backend. It would require adding
additional "if" statements in prefs.html but this shouldn't add much overhead.
My specific use case is that I'm using a http auth backend where I only get
the codes 403 for wrong username/password sets or a 200 one for valid
combinations (+some pretty useless data like a username which I already
have;) After that the user has to enter the rest of his details by himself,
especially the email address.
