Chain doesn't work after a Fx.Tween's fade(0) calling

Hi. I noticed on 1.4.1 that the `chain()` method of `Fx.Tween` doesn't work after a call to `fade('out')` or `fade(0)`.

Here you can test it in a fiddle: http://jsfiddle.net/TSRV6/

If you try to switch to previous Mootools version (1.3.2), it's all ok.
It works with 1.4.1 if you try `fade(0.0001)` instead of `fade('out')` or `fade(0)`.

I'm using Firefox 7.0.1.
