This crash appears to only be affected in SMP only.

If you look at the picture, basically to reproduce the constant crash, you get a heap of baby chickens on the half slab then break the block thats normally tot he left of that, which allows the baby chickens to spread out to that adjacent block, you then use a piston with a solid block and activate it to push the block to where the chickens are an it instantly crashes the server with Ticking Entity. Crash Report Attached