Endermen's heads open and close briefly when shot while riding boats or minecarts

Short description of the issue

When an endermen in a boat/minecart is shot by an arrow or some other projectile they open and close their mouth briefly before opening their mouth when angry.

Steps to reproduce this issue

1. Put an enderman in a boat/minecart.

2. In survival mode, shoot the enderman with a projectile.

Expected result

The enderman will open its mouth once.

Actual result

The enderman opens its mouth, closes its mouth, and opens it again.