'Parse the field as an iso string but prevent dateutils from defaulting the day or month while
allowing it to default the other fields.'

def _parse_date_wo_default_month_day(self, field):

    result = dateutil.parser.parse(field, default=self.PREVENT_DEFAULT_DAY_MON_SEED1)
    result_other = dateutil.parser.parse(field, default=self.PREVENT_DEFAULT_DAY_MON_SEED2)
    if (result != result_other):
        log.warning('Field    {0}    is    missing    month    or    day'.format(self.name))
        return None
    if (result.tzinfo is None):
        result = result.replace(tzinfo=UTC)
    return result
