实在找不到地方发2.7beta2的bug了，还让不让反馈bug呀，发在这里，希望有人重视一下

foreach($ids as $usergroupid => $new_position)
   {
    if ($usergroupid > 0)
    {
     $orderssql .= " WHEN usergroupid = $usergroupid THEN $new_position";
     $ugids .= ",$usergroupid";
    }
    
    $forums->func->fetch_query_sql(array('displayorder' => intval($new_position)), 'usergroup', 'usergroupid=' . $usergroupid);
   }
   if (!empty($ugids))
   {
    $DB->query_unbuffered("UPDATE " . TABLE_PREFIX . "thread
     SET displayorder = CASE $orderssql ELSE 0 END
     WHERE tid IN (0$ugids)");
   }