Work around RHBZ#1625572 (both g-i-s modes running)
    
    RHBZ#1625572 is for gnome-initial-setup running in 'first login'
    mode after it's already run in 'user creation' mode (which isn't
    meant to happen). This works around that so the subsequent tests
    can run. We don't soft-fail because meh.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>