When you drink an invisibility potion and look at some one whit an item in your hand and go to 3rd person view you can see that your arm is swinging as the other player does it, also tries to block if the other player does it.

This also applies to heads if you put a mob head on you it will mimic the players head movements.

What I expected to happen was...:
Head should look where you are looking, and you should not mimic movment

Steps to Reproduce:
1. Have another player nearby, and drink a invisibility potion
2. Go in to 3rd person view.
3. Equip an item in your hand
4. Have the other player swing or block.
5. you will now se that your character is doing the same.