Return the directory the config file is located in.

    This enables us to use relative paths in config values.

def get_config_directory():
    """Return the directory the config file is located in.

    This enables us to use relative paths in config values.

    """
    # avoid circular import
    from .commands.stacker import Stacker
    command = Stacker()
    namespace = command.parse_args()
    return os.path.dirname(namespace.config.name)