In my survival world, I was playing in the snapshots normally when I received an unexpected crash. I looked through the report and found fairly quickly that somewhere in the nether(for that was where I was) a baby zombie pigman chicken jockey had spawned and that had crashed the game. About fifteen minutes later the exact same thing happened again in the overworld, and after hashing through the report once again I discovered that this time a regular chicken jockey had crashed the game.

1. wait for a baby zombie(pigman) chicken jockey to spawn

2. see if the game crashes