why is datachanged event not called

Can you look at this fiddle and see why my event listener for datachanged event is not being called when I remove a record from the store with drop. Is this a bug?

Select a row and click delete. Expect the datachanged event to get called because drop documentation says "When a record is dropped, it is automatically removed from all association stores" and datachanged "Fires whenever records are added to or removed from the Store."

http://ift.tt/160bsDg

why is datachanged event not called