Falling off 49 blocks in a boat kills you

When you fall off a height of 49 blocks in a boat in survival, you die

What I expected to happen was...:
At every other height you fall down, fall damage is neglected

What actually happened was...:
I died

Steps to Reproduce:
1. Pillar up 49 blocks 
2. Enter a boat
3. Row off the pillar

4. You are dead (make sure your fall is exactly 49 blocks)