This has only happened once while playing the 12w36a snapshot but the resulting game crashes forced me to delete the world.

While riding a saddled pig with Carrot on a Stick equipped, the game suddenly crashed. When the world was loaded again I was no longer on the pig and then as soon as the saddled pig was reloaded, the game crashed again.

After several attempts at reloading the world I was able to get far enough away from where I was when the game crashed that the pig was not reloaded, the game did not crash. It only crashed again when I went back to the area and the pig was reloaded.

(Not sure if caused when pig is reloaded or just when rendered)

As mentioned before this has only happened to me once, I have tried searching for similar problems but it seems no one has reported anything like this occuring.

The bug may have been fixed through the following snapshots but I felt I had to report this just incase it's still lurking in the code. It does cause the affected world to become unplayable so this must be checked before the release of 1.4