dojox/form/CheckedMultiSelect can not be cleared programatically probably due to a bug in dijit/form/_FormSelectWidgetMixin

Description:
I have a CheckedMultiSelect widget configured to allow multiple values, if I call:

mywidget.set("value", ["value1", "value2"]);

Selects the two values as expected.
If I call:

mywidget.set("value", []);

Expected behaviour:
No value should be selected in the widgets and all the checkboxes should appear unchecked.

Actual behaviour:
The already selected checkboxes remain checked. Interestingly though, if you click in a different checkbox than the already selected one you will notice that the others are unchecked.

Doing mywidget.set("value", "") doesn't solve the problem either.

How to reproduce:
See this Fiddle: http://jsfiddle.net/41Lh0zoj/

More info:
I think that the problem is exactly here: https://github.com/dojo/dijit/blob/041948280c2b9ba102c52c35f02d80901fce6b93/form/_FormSelectWidget.js#L462

I don't think that checking 'typeof val[0] == "undefined"' is right, because like in this case, val might be an empty array and that seems perfectly fine to me. Doing this additional checks avoids calling _setDiaplsy and _updateSelection which is causing the reported problem.