模型动画修改动画播放速度不生效

Creator 2.x
#1 
    attackClip.events = [{ frame: 0.5, func: "attack", params: [] }]
    this.init();
    var clip = this.getClipByName("Atk02");
    clip.speed = 0.5;
    clip["frameRate"] = 60;
    setTimeout(() => { attackClip.events = null;console.log(clip)},5000)

播放速度修改不生效 ，动画事件不能移除，设置为null 还是会继续执行

这是bug吗