'Update release_date (eta) info only
@param media_id: document id
@return: dict, with dates dvd, theater, bluray, expires'

def updateReleaseDate(self, media_id):

    try:
        db = get_db()
        media = db.get('id', media_id)
        if (not media.get('info')):
            media = self.update(media_id)
            dates = media.get('info', {}).get('release_date')
        else:
            dates = media.get('info').get('release_date')
        if ((dates and ((dates.get('expires', 0) < time.time()) or (dates.get('expires', 0) > (time.time() + (604800 * 4))))) or (not dates)):
            dates = fireEvent('movie.info.release_date', identifier=getIdentifier(media), merge=True)
            media['info'].update({'release_date': dates})
            db.update(media)
        return dates
    except:
        log.error('Failed    updating    release    dates:    %s', traceback.format_exc())
    return {}
