Minecraft Snapshot 14w26c /summon bug

I /summoned a wither skeleton with a steve head {SkullOwner:""} (Command Block)

I thought this would spawn a wither skeleton wearing a steve head

What actually happened was...........
Uhh... Try it yourself... its WEIRD
I cant explain sorry...

To find the bug:
1a. Launch minecraft on 14w26c
1b. Create a world if you dont have one already
2. Place a command block
3. Enter the command: /summon Skeleton ~ ~1 ~ {SkeletonType:1,Equipment:[{id:},{id:},{id:},{id:},{id:skull,Damage:3,tag:{SkullOwner:""}}]}
4. Power the command block
5. There's the bug
6. If you kill the skeleton, your screen blacks out (at least mine did) and doing anything (Open pause menu, open inv...)
7. At this point I closed minecraft...