Villager GUI closes immediately if villager is on a slime block

What I expected to happen was...:
I expect to be able to trade with villagers that are in range.

What actually happened was...:
The villager refuses to trade if he is standing on a slime block.

Steps to Reproduce:
1. Trade with a villager that is standing on a slime block and the GUI will close too fast to use it.
2. Move the same villager one block away, onto a non-slime block and he will trade normally.
3. Move the same villager back onto a slime block and the problem repeats.

This occurs even if the villager is motionless on the slime block.

I notice there are reports of this being resolved for older versions of Minecraft, but it seems to have re-appeared in newer versions.