Milking Cow Bug

I'm Playing Survival (Singleplayer) And I Was Going To Make A Cake So I Milked A Cow And Me Bukkit Disappears.
The Bugs Works In:
-Singleplayer
-Lan World
-Multiplayer
ONYL IF UR SURVIVAL MODE!

What I expected to happen was...:
Tht I Get A Bukkit Whit Milk When I Milk A Cow.

What actually happened was...:
The Bukkit Disappears When I Milked Him.

Steps to Reproduce:
1. Make A Bukkit And Find A Cow.
2. Milk The Cow.
3. Bukkit Disappears.