Player grace period missing for damage

In the latest snapshot the mercy period was removed, meaning that damage is done as fast as people can click at another person rather than limited to a certain speed.

This makes no sense given the developer's stated aims to remove spam clicking.

I recorded a clip of the bizarrely fast attack speed
https://youtu.be/ONj_aFU8_Lg

Edit: I've learned that this applies to other forms of damage as well.

Steps to reproduce:

1: log into a multiplayer server in 16w04a

2: go into survival mode and find some lava

3: jump in.

Or

1: log into a multiplayer server and spam click at another player.

2: observe nearly every hit land, faster than possible in 1.8