15w44A Mob Bug

Put the summary of the bug you're having here

What I expected to happen was...:
The Mob to attack, and it wasn't burning in the sun

What actually happened was...:
The mob stood still and wasn't on fire from the sun

Steps to Reproduce:
1. I just found it I don't really know how to do it.

Here is a video I uploaded showing it: https://youtu.be/RIF1RSEldao