What I expected to happen was...:
The skeleton being hit by the diamond helmet, or wearing the helmet, after I hit it with it
What actually happened was...:
The game crashed and stopped working.
Steps to Reproduce:
1 Open existing world in creative mode (previous version of snapshots)
2. Hold diamond helmet in right hand still in creative mode
3. Rightclick on skeleton with diamond helmet
Environment
Minecraft Version: 15w49a
Operating System: Windows 10 (amd64) version 10.0
Java Version: 1.8.0_25, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode),
Incomplete without a crash report. Please attach it so the issue can be diagnosed.