In the new snapshot, 14w06a, I was playing around with the CanPlaceOn and CanDestroy commands. When I went into adventure mode, I discovered a crash. After multiple tests, I think that I found out that when taking any amount of time to break a block (Basically if in gamemode 0 or 2), with anything that can break a block, the game crashes. I used this command in adventure, /give nbairen minecraft:iron_pickaxe 1 0

, and it crashed. I even tried breaking it with my fist. No good. I looked and I think that this is the first of this report, but sorry if it's a duplicate. Please fix, thanks.
Crash report added as attachment.