static function ensurePattern($pattern)
 {
     $hb = Homepage_blacklist::staticGet('pattern', $pattern);
     if (empty($nb)) {
         $hb = new Homepage_blacklist();
         $hb->pattern = $pattern;
         $hb->created = common_sql_now();
         $hb->insert();
         self::blow('homepage_blacklist:patterns');
     }
 }