Workaround F26 base image g-i-s issue for upgrade tests too
    
    Since April there's been some kind of issue in the F26 base
    image which means gnome-initial-setup doesn't run on the first
    user login (as it should). The F25 base image is fine. I've
    not yet had the time to look into this.
    
    I put a workaround in place to prevent this problem causing
    false fails of update tests that boot from the F26 base image,
    but didn't apply the same workaround to upgrade tests, which
    is why upgrade tests from F26 Workstation always fail - they
    expect g-i-s to run on first login (which happens after the
    upgrade, in upgrade tests) and it doesn't. So let's just extend
    the workaround to apply to upgrade tests too, for now, until we
    can figure out why this happens.