This game breaking bug allows players to respawn in hardcore mode upon death without need to close game and edit game files. 

What I expected to happen was...

to stay dead upon dying

What actually happened was...:
the ability to respawn in hardcore

Steps to Reproduce:
1. Die in a minecraft world set at hardcore difficulty and click the spectate world option.
2. open game menu by clicking escape and open the world to lan with cheats enabled
3. then go into chat and type in command /gamemode survival and you will be placed back into the world in survival mode as if you never died.