sortable behaviour inconsistent with droppable/draggable

[bago]

I see sortable implements this feature:

knockout-sortable/src/knockout-sortable.js

Line 130 in 426300f

$.extend(true, sortable, ko.bindingHandlers.sortable);

Is that "wanted"?
The documentation doesn't document that behavior, that would only be needed if you want to be able to put default options directly in the binding by using

ko.bindingHandler.sortable.options = {}

Also, the same behaviour cannot be find in draggable and droppable wrappers.