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 setup_run_environment(self, env):
        bashrc = self.prefix.etc.bashrc
        try:
            env.extend(EnvironmentModifications.from_sourcing_file(
                bashrc, clean=True
            ))
        except Exception as e:
            msg = 'unexpected error when sourcing OpenFOAM bashrc [{0}]'
            tty.warn(msg.format(str(e)))