When a player is in effect Leaping(id:8), level 128 or above(but no more than 250), he can't jump. However, when he was hit by other players, he will be off ground for a shot while. During this period if that player is hit once more, he will burst into sky like a rocket and fall to death.
Steps to reproduce:
1. First you need at least two players, with permissions that can execute commands.
2. One type /effect @p minecraft:leaping 2 128, hit Return.(128 can be replaced by any number between 128 and 250)
3. The other player will see the effect particle(mobSpell), then just hit the guy crazily!
4. You will find the one who's with Leaping boost will fly into sky.

What I expect is, the player with Leaping should not be hit to fly up. It must be a bug.