I was standing on an anvil, holding shift to crouch but I still fell off of the anvil.

What I expected to happen was...:
Holding shift would stop me from falling off of the anvil, like it does with all other blocks.

What actually happened was...:
I fell off the anvil.

Steps to Reproduce:
1. Place an anvil, making sure it isn't adjacent to any other blocks that you could walk on to.
2. Stand on the anvil.
3. Hold shift (or equivalent binding for crouch) and try to walk off the anvil.
4. Fall into lava and lose all your diamonds, asking yourself if making this bridge out of anvils was the best idea.