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_url_rev_and_auth(cls, url):
        # type: (str) -> Tuple[str, Optional[str], AuthInfo]
        """
        Prefixes stub URLs like 'user@hostname:user/repo.git' with 'ssh://'.
        That's required because although they use SSH they sometimes don't
        work with a ssh:// scheme (e.g. GitHub). But we need a scheme for
        parsing. Hence we remove it again afterwards and return it as a stub.
        """
        # Works around an apparent Git bug
        # (see https://article.gmane.org/gmane.comp.version-control.git/146500)
        scheme, netloc, path, query, fragment = urlsplit(url)
        if scheme.endswith('file'):
            initial_slashes = path[:-len(path.lstrip('/'))]
            newpath = (
                initial_slashes +
                urllib_request.url2pathname(path)
                .replace('\\', '/').lstrip('/')
            )
            after_plus = scheme.find('+') + 1
            url = scheme[:after_plus] + urlunsplit(
                (scheme[after_plus:], netloc, newpath, query, fragment),
            )

        if '://' not in url:
            assert 'file:' not in url
            url = url.replace('git+', 'git+ssh://')
            url, rev, user_pass = super(Git, cls).get_url_rev_and_auth(url)
            url = url.replace('ssh://', '')
        else:
            url, rev, user_pass = super(Git, cls).get_url_rev_and_auth(url)

        return url, rev, user_pass