def refresh(cls):
        """This gets called by the refresh function (see the top level
        __init__).
        """
        # clear the old values in _flag_map
        try:
            del cls._flag_map["t"]
        except KeyError:
            pass

        try:
            del cls._flag_map["-"]
        except KeyError:
            pass

        # set the value given the git version
        if Git().version_info[:2] >= (2, 10):
            cls._flag_map["t"] = cls.TAG_UPDATE
        else:
            cls._flag_map["-"] = cls.TAG_UPDATE

        return True
This gets called by the refresh function (see the top level
        __init__).