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 get_repository_root(cls, location):
        loc = super(Git, cls).get_repository_root(location)
        if loc:
            return loc
        try:
            r = cls.run_command(
                ['rev-parse', '--show-toplevel'],
                cwd=location,
                show_stdout=False,
                stdout_only=True,
                on_returncode='raise',
                log_failed_cmd=False,
            )
        except BadCommand:
            logger.debug("could not determine if %s is under git control "
                         "because git is not available", location)
            return None
        except InstallationError:
            return None
        return os.path.normpath(r.rstrip('\r\n'))