def get_dir_from_zipfile(zip_file, fallback=None):
    """Return the name of the root folder in a zip file.

    :param zip_file: a :class:`zipfile.ZipFile` instance.
    :param fallback: if `None`, the name of the zip file is used. This is
        returned if the zip file contains more than one top-level directory,
        or none at all.
    """
    fallback = fallback or zip_file.filename
    directories = [name for name in zip_file.namelist() if name.endswith("/")
                   and len(PurePath(name).parts) == 1]
    return fallback if len(directories) > 1 else directories[0]
def main():
    parser = argparse.ArgumentParser()
    parser.add_argument("day", help="The day of the results, with format yyyymmdd")
    args = parser.parse_args()
    install_autopkgtest_results_formatter()
    with tempfile.TemporaryDirectory(dir=os.environ.get("HOME")) as temp_dir:
        clone_results_repo(temp_dir)
        format_results(temp_dir, ACTIVE_DISTROS, args.day)
        commit_and_push(temp_dir, args.day)