[Bug] Wiping items with anvils

Minecraft Username:
314.

Brief Description:
Items can be wiped using the anvil restrictions.

Instructions:
Open the anvil GUI. Click on an item (preferably not a very expensive one) to make it stick to your cursor.
Shift-click another item to move it to the anvil slots. As intended, the GUI closes. As not intended, the first item disappears.

How many times did you recreate this bug?:
One involuntary attempt, two voluntary attempts, three resulting occurrences.
Result:
The second item is ejected, the first item is wiped without a trace.

Expected Result:
To have all items ejected.

Evidence:
#IAEAJFF3 (Max fortune pickaxe) tool logs end when the tool was used within the anvil (as stated by Clar).
#I9K9QYED (Stone flux pickaxe) may have been wiped accidentally during purposeful testing.