// match conversations - first try ostatus:conversation
// next try thr:in_reply_to
if($conv_id){
$c=q("select parent_mid from item left join iconfig on item.id = iconfig.iid where iconfig.cat = 'ostatus' and iconfig.k = 'conversation' and iconfig.v = '%s' and item.uid = %d order by item.id limit 1",