Villagers plays agree/disagree sound when using a bundle while trading

When using a bundle while trading with a villager, the villager will make the agree or disagree depending on when is in the trade slot.

Steps to Reproduce:

1. Give a bundle and random items
2. Get an emerald
3. Summon this villager

   /summon villager ~ ~ ~ {VillagerData:{type:plains,profession:farmer,level:3},Offers:{Recipes:[{maxUses:1,buy:{id:emerald,count:1},sell:{id:dirt,count:1}}]}}

1. Put the emerald in the villager's trade slot but do not trade with it
2. Use items into the bundle and take them out
3. Remove the emerald and put any other item into the trade slot
4. Repeat step 5

Observed Results:
The villager will play the agree sound when there is an emerald (step 5) or the disagree sound when there is any other item in the trade slot (step 7).

Expected Results:
The villager should not play the agree or disagree sound unless we are interacting with the trade slots.

Screenshots/Videos:
http://youtu.be/GgVbA5cv2yQ