Crash - Loading entity NBT

I got a crash when a minecart was spawning a cow.

What I expected to happen was:
This crash didn't happen in 1.5.2.

What actually happened was:
I got a crash in 13w22a.

Steps to Reproduce:
Note: I'm going to leave you with the map to reproduce the bug (make sure you use 13w22a) . I'm not going to send the link to it as this is only for bug reproducing purposes.
1. Load the map.
2. Go to choose map.

A crash should appear.