tom-buf

    # XXX TODO: Since Singularity normally supports local paths to image files
    # or directories, it's possible someone might try to pass that.  We're
    # treating those as Docker image names unqualified by docker://, which may
    # cause confusion.  Doing:
    #
    #   assert url.scheme or not Path(url.path).exists()
    #
    # might help… or it might cause false positives and different confusion.
    # Let's not for now and wait and see.
    #   -trs, 5 Jan 2023