A minecart existing in the world will despawn when the player moves out of range. This issue is present for both minecarts that I have placed since the 15w32a update and ones that existed before the update. I have noticed this for minecarts with chests, but it seems all types of minecarts are affected.

What I expected to happen was...:
My minecarts to not despawn.

What actually happened was...:
After initially loading the cart, they had despawned when I re-entered the area (travel away from the minecart).

Steps to Reproduce:
1) Place minecart in world.
2) Travel a sufficient distance so that the chunk no longer renders.
3) Return to minecart.
4) Mourn the loss of any items in the minecart.