Potions thrown by witches have no effect

Put the summary of the bug you're having here

What I expected to happen was...:
To be given a potion effect.

What actually happened was...:
I was given no effect, as the potion was textured like the blank splash potion.

Steps to Reproduce:
1. Load a world in 15w46a and have a witch spawn.
2. Go into survival and walk up to the witch.
3. The witch will throw potions with no effect.