Corrupt Health Boost Not Working?

"Corrupt" health boost effects do not decrease health. A "corrupt" potion effect is when the amplifier is above or equal to 128.
Steps to reproduce:
1. Open a world that has cheats enabled.
2. Run "/gamemode 0".
3. Run "/effect @p 21 15 131".
What is supposed to happen: You should lose hearts.
Result: You gain a HUGE amount of hearts.