SAFETYBELT, Only set if we really have an identifier

def _cron_id(cron):
    '''SAFETYBELT, Only set if we really have an identifier'''
    cid = None
    if cron['identifier']:
        cid = cron['identifier']
    else:
        cid = SALT_CRON_NO_IDENTIFIER
    if cid:
        return _ensure_string(cid)