When using /summon Zombie ~ ~ ~ the Zombie can attack the player immediately

Summary: When the Player is using /summon Zombie at the current position, after the Zombie is summoned, it is able to immediately attack the Player.

How to reproduce:
1. Create world with cheats enabled.
2. Perform this command: /summon Zombie ~ ~ ~

{IsBaby:0}

3. If you aren't attacked immediately, repeat until you are.

Notes:
1. Also affects 16w04a.