1.9 Ender Dragon bug?

Hello!
This morning I had to play Minecraft 1.9.
I was killing the Ender Dragon, Then I've found a bug.
That bug was a very easy way to kill Ender dragon,
I've been using it can easily kill.

This bug, When the Dragon came as a blow when it does not hit me Bedrock's.

By filing with the translator do not even hard to hear.