You don't take damage in the void while gliding with an elytra

How to reproduce:
1. Get yourself an elytra
2. Dig all the way down trough bedrock (you need to be in creative)
3. Start gliding with the elytra below the bedrock
4. You can keep flying down without taking damage or getting killed

Notes:

• When you take of the elytra you'll keep gliding without elytra

• You can't run any commands

• If you try to save and quit to title the game will get stuck and you need to force crash the game

Log:

[18:14:51] [Server thread/INFO]: stebo02 joined the game
[18:14:51] [Server thread/WARN]: Can't keep up! Did the system time change, or is the server overloaded? Running 4362ms behind, skipping 87 tick(s)
[18:14:51] [Server thread/INFO]: Saving and pausing game...
[18:14:51] [Server thread/INFO]: Saving chunks for level 'world'/overworld
[18:14:52] [Client thread/INFO]: Loaded 13 advancements
[18:14:52] [Server thread/INFO]: Saving chunks for level 'world'/the_nether
[18:14:52] [Server thread/INFO]: Saving chunks for level 'world'/the_end
[18:15:55] [Client thread/INFO]: [CHAT] Saved screenshot as 2018-04-12_18.15.55.png