cloning air on containers dumps items

Windows_Minecraft - Release_920093
(Beta 1.5.0.3)

Summary:

cloning air over containers causes them to dump items.

Impact: 
cloning over containers is important as cloning is the best way to change rooms and other things. If you want to clone over a chest to remove it, it dumps the items and this may not be wanted.

Repro Steps:

1. Open the attached “clone setblock bug world”
2. Press the button at MCM-256 to clone air over containers

Observed Results:
Clone was successful but items were dumped on the ground, this occurs regardless is tiledrops is on or off.

Expected Results:
the clone should put air where the containers are without dumping the items. Java handles it this way.

Screenshots/Videos attached:
repro world attached.