Locked villager trades still allow trading, but with different items.

Trying to trade with emeralds in locked trade slots, even when it doesn't accept emeralds as a trade item, results in being able to trade for items in other trade menus the villager offers.

To reproduce:

1. Unlock some trades on a villager.
2. Lock out a trade on the villager that doesn't involve emeralds.
3. Try trading with various numbers of emeralds.