When in the End dimension, entity and terrain generation corrupts.

What I expected to happen was...:
When punching endermen, they would react. When exiting fly mode in Creative mode, you would fall down onto the ground. When entering commands, they would work.

What actually happened was...:
Endermen were static, punching them did not affect them. When exiting fly mode, you would float down through blocks. However in survival mode, when falling through blocks you wouldn't take any damage, when you reload the world, you appear back at the starting position and the same thing happens. Commands do not respond and command feedback does not show.

Steps to Reproduce:
1. Load a world in 15w32b
2. Corrupt forever.
OR
1. Kill the "original" Enderdragon and activate the ender gateway.
2. Commit suicide.
3. Spawn the Enderdragon again and kill him.
4. Enter the other gateway.
5. Enjoy your corrupted world WINK