Reloading a world while player is in moving Minecart or riding a horse is glitchy in F5 mode

If you load a world while in a minecart the player is gitters back and forth in F5 mode.

How to reproduce:
1. Create a world and get in a minecart. (Doing this on a horse also works)
1.a (Make sure it is moving to get see it better.)
2. Reload the world. Go into F5 mode while in the minecart.
Video from: Dirk Sohler. Link: http://www.youtube.com/watch?v=SYBZ74aCSSE