Inventory & Spawnpoint wipe

What I expected to happen was...:I expected to join my minecraft server, which I just updated to 14w10b from 14w08a, and be at my house, and to have all the stuff in my inventory from when I last logged off

What actually happened was...: Instead of being at my house, I was at the world spawnpoint and my inventory was empty
Describe what happened here

Steps to Reproduce:I do not know why this happened or how to trigger it beside the fact that it happened when I generated a world in 1.7.4 and then updated it to 14w08a and then to 14w10b