I started a standard world in the last snapshot however now in this, the latest snapshot zombies don't track me if they are situated in water.

There was a skeleton out of the water which followed me.

The zombie didn't follow me even if I was in the water.

Steps to reproduce.:

1) find a zombie which is in water

2) note that even if you are in close range it does not follow you even if you follow it into the water.

I haven't tested this with other mobs though I will update this if any others are affected. Possibly humanoid mobs will knowing how the AI is most likely implemented