What I expected to happen was for my Resource Pack to change to the Resource Pack for Paper Cut-Out Texture Pack I'd just made using the Minecraft TextureEnder you provide on Mojang.com

What actually happened was that when I changed to the pack, it crashed my game. Same result when I went back to the default pack.
Steps to Reproduce:

1. Go on a Mac and enter the game using 13w24b
2. Get a Resource Pack installed onto your Step 1 game
3. When on the front page, Go into the options menu, and click on the Resource Pack button
4. Change your Resource Pack to the other one you have.
5. Congratulations!! Your game (Most likely!) has crashed!!!