Put the summary of the bug you're having here

What I expected to happen was...:
I would see something like "When applied: -5% strength" when I waved my mouse over a weakness potion.

What actually happened was...:
I saw "When applied: "

Steps to Reproduce:
1. Go into Minecraft 13w25b and go in creative (easiest way to get a potion).
2. Put cursor over any weakness potion in "Potions"