Redstone output of item frame not updating when destroying item frame by piston / killing by /kill @e[type=ItemFrame]

When I Make An System To Use The New Implemented Funcion, The Item Frame Item Detector, When I Place An Piston To Break The Item, And Active It, The Redstone Goes To An Infinity Loop!!! Some Screenshots:

1'st :
http://imgur.com/cJp5FTU
I Have Made The Simple System, And Not Activated It.

2 :
http://imgur.com/yNdZHZx
Here I Have Activated The System, The Piston Brokes The Item-Frame And It's Continue Sending Redstone Signal.

3 :
http://imgur.com/iel1NXe
And Here I Have Broke The Piston, And It's Continue Sending Redstone Signal.

Steps to reproduce:
*Put an item frame at a block
*Put a comparator output to the block
*Put some item in the item frame
*Destroy the item frame by piston
--> Comparator output does not change until a new item is placed in a new item frame