Shift-clicking breaks Villager trade interface.

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Put the summary of the bug you're having here

Shift-clicking breaks Villager trade interface.

What I expected to happen was...:
It should have performed as many trades as possible with the items involved.

What actually happened was...:
It either did one or no trade and activated the "Trade other items to unlock!" function. This cannot be undone from what I can tell. It is often permanently broken. (It's also particularly common among Villagers created with a Spawn Egg.) Side Bug: Sometimes during a trade (regardless of if the shift button is used while clicking) the trade will go through, the Villager will give the player an emerald, but the items being given to the Villager remain in the player's inventory. (I don't intend to be the village con-artist, so it would be nice to have this fixed.  ) This happens most often on the trade action during which the offer becomes locked.

Steps to Reproduce:
1. Open the Villager trading interface.
2. Offer enough items to receive an emerald, preferably a multiple (if 11 are required, offer 22.)
3. Shift-click the given emerald. The trade will often become unavailable.