Emerald Duplication

If you exit out of the trading menu after trading using ESC then almost all of the emeralds you spent away will get thrown on the floor

What I expected to happen was...:
When I exited the trading menu with ESC only any emeralds left in the trading menu would get thrown in front of me

What actually happened was...:
It threw most of what I spent away on to the ground so it was duped

Steps to Reproduce:
1. Open the trading window with a villager that is selling something (it doesn't work when you sell something to the villager)
2. Put some emeralds in the slot then shift click to buy as much as possible
3. Press ESC, the emeralds you spent should be thrown on the ground

Here's a video for it:
http://www.youtube.com/watch?v=0NqE5SX45bo&feature=youtu.be