What I expected to happen was...:
Normal Minecraft gameplay.

What actually happened was...:
My world turned black. Also tested on a server, it turned black there as well. Animal and player textures are normal, as well as some items. Most block item textures also turned black.

Steps to Reproduce:
1. For snapshot/ survival: Start a world, break a block, watch as the world turns black.
2. For 1.7.2: Join a server, play for a bit, watch as the world turns black.

Discoveries
It seemed to fix itself when I applied a resourcepack, although it quickly became black again. After a few tries of this, it stopped working.