Bug Summary:
-When making a pen for any type of passive mob (Seen it with Cows, Chickens, Sheep, Rabbits, Cats, Wolves, Horses etc) the mobs get stuck in the hit-box of the fence. Then the mobs stay in the hit-box of the fence forever until a player manually pushes them out of the hit-box. After "freeing" the mob it does not take long until the mob once again walks near the fence and gets stuck. Using a lure food (carrots, wheat or seeds) does not make the mob move once it is stuck in the fence blocks hit-box.

What I expected to happen was...:
-What 'i expected to happen was that the mobs would wander around in the pen and be able to walk near the fence blocks without getting stuck.

What actually happened was...:

• The mob wanders around a short period of time and gets stuck to fence block once it gets close to the fence block.

Steps to Reproduce:
1.Make a cow pen (with any type of fence) any size and wait a short period of time
(done)

The screenshot is from the 15w 34b snapshot.

Thanks for reading Mojang!