critpath.py: handle the 'release gap' problem
    
    There's this infamous issue with using release data from Bodhi
    (as this script does) - a new release is marked 'stable' in
    Bodhi several days before it's actually accessible in the normal
    location for 'stable' releases in the mirror system (even on
    dl.fp.o). If you just trust Bodhi to tell you when a release is
    stable and assume you can find it in the stable path, for a few
    days each cycle this will fail. I somehow failed to notice this
    would be a problem for critpath.py when adjusting it to use Bodhi
    data and be run daily, but...obviously it is:
    https://pagure.io/fedora-infrastructure/issue/11247
    This is a somewhat hacky way to handle it, but it's quite easy
    and doesn't require too much change to the code.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>