Incorrect Query Result (MySQL Bug 68897) in MariaDB 10.0.14

CREATE TABLE  `features_test` (

  `param` int(11) NOT NULL,

  `idx` int(11) NOT NULL,

  `text` varchar(255) default NULL,

  PRIMARY KEY  (`param`,`idx`)

) ENGINE=InnoDB DEFAULT CHARSET=utf8;

INSERT INTO `features_test` (`param`, `idx`, `text`) VALUES

(1, 0, 'select'),

(1, 1, 'Kabel mit Stecker 5-polig'),

(1, 2, 'Kabel ohne Stecker'),

(2, 0, 'number'),

(2, 1, '22'),

(2, 2, '25');

CREATE TABLE `idList` (

  `id` int PRIMARY KEY

);

INSERT INTO idList VALUES (1),(2),(3),(4);

SELECT idList.id AS id, T.text AS xtext,GROUP_CONCAT(T3.text) AS optionen

FROM idList

LEFT JOIN features_test AS T  ON(T.param=idList.id AND T.idx=0 )

LEFT JOIN features_test AS T3 ON(T3.param=idList.id AND T3.idx>0 ) 

GROUP BY idList.id

ORDER BY id ASC;

SELECT idList.id AS id, T.text AS xtext,GROUP_CONCAT(T3.text) AS optionen

FROM idList

LEFT JOIN features_test AS T  ON(T.param=idList.id AND T.idx=0 )

LEFT JOIN features_test AS T3 ON(T3.param=idList.id AND T3.idx>0 ) 

GROUP BY idList.id

ORDER BY id DESC;