Bug#613824: Move session choosing earlier

[Tollef Fog Heen]

It would be useful if this could be moved earlier.  I'm using a yubikey
and challenge-response authentication so I first plug in the key, then
choose a user and is automatically logged in.  It would be better if I
could choose the session before choosing the user like it used to be.

A workaround in my case is to not plug the key in, choose a user, choose
session, enter a blank password (so I get «wrong password»), then insert
yubikey and then choose user again.  It's a bit tedious, really.

-- 
Tollef Fog Heen
UNIX is user friendly, it's just picky about who its friends are