Windows 7 32-bit, 32-bit Java version 1.7.0_07 by Oracle Corporation
What I expect to happen : Wither spawn normally like in 1.4.7
What actually happen : When the player create a Wither, only the Wither Skeleton Skull and the Soul Sand below it is completely gone. The other become a ghost block (can't created into another Wither, when destroyed in survival it take the same time as the normal block but doesn't drop anything).
How to trigger :
1. Create the Wither
*Happen in creative too
MC-6872 Upon creating the wither, It leaves ghost blocks