How to reproduce this bug:
1.Build or instal an tnt run map
2.Place a few blocks under the TNT lava or water and use when using water a detect command that kills you when you fall in the water
3.Play the TNT run map or watch how an other person plays it

What happens:

When having lava under the TNT you catch on fire even you didn't touched it. When having water and a detect command (execute @a ~~~ detect ~~~ water 0 kill @s) you die without touching the water. If you watch someone playing TNT run it looks like he falls down but then gets teleported back up.

What should happen:
You should be playing TNT run without catching on fire or die when you not fell down.