Item frame causing duplication when loading map (causing / caused by stack overflow)

Attached screenshot and minimal world repro. If you stand at the location indicated in the screenshot and save/reload the world, you will hit the bug.

Root cause has been narrowed down to:
Item frame with some contained item at X=0 / Z=0 in chunk
Mounted on block in adjacent chunk
Behind that block, a comparator is sensing the item frame

Stand in a chunk adjacent to the chunk containing the item frame, save and load the world, and all entities in the chunk with the item frame will be duplicated a huge number of times.

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From MC-56077:

This is an item duplication glitch that involves the new comparator measuring item frame feature in snapshot 14w18.

How to Replicate This Bug:
1.) Find the east/west edge of a chunk. (Preferably using F3)
2.) Place any redstone current-carrying block on the west side of the chunk edge.
3.) Place an item frame on the block, facing east.
4.) Place a comparator next the block, pointing the opposite direction that the item frame is facing, so that the comparator is in a different chunk than the item frame.
5.) Put any block you want to duplicate into the item frame.
6.) Quit and re-join the world. You will now have a stack of item frames and the item you put in the frame.