Put the summary of the bug you're having here
What I expected to happen was...:
It would sit there as a model, devoid of life
What actually happened was...:
It summoned a wither
Steps to Reproduce:
1. build a wither spawn template (on peaceful)
2. replace the soul sand blocks with soul soil blocks
3. beware the explosion!
Comments 4
Yes, see the Minecraft wiki.
This is intended behavior that was added as a feature a few snapshots back, right?