Round the user picture on lock dialog.

All user dialogs (Linux, Windows, Mac, Android, etc..), or any
representation of a user as an avatar in the web are round
images.

Also, it shows an emblem icon to note that it is logged in as
in other dialogs.

Both options can be made configurable by the user very easily,
but at least (IMHO of course), I think it respects the
preference of the majority of users.
2 jobs for !13 with round in 2 minutes and 12 seconds (queued for 7 seconds)
latest detached
Status Name Job ID Coverage
  Build
passed build #19249

00:00:54

 
  Distcheck
passed distcheck #19250

00:01:18