Mobs don't panic when hit with a summoned or dispensed potion of harming

The Bug:

Mobs don't panic when hit with a summoned or dispensed potion of harming.

Steps to Reproduce:

1. Build the setup shown in the attachment below. setup.png
2. Obtain a potion of harming and place it inside the dispenser.
3. Summon a cow on the diamond block.
4. Activate the dispenser and observe the cow's behavior.
5. Take note as to whether or not mobs panic when hit with a summoned or dispensed potion of harming.

Observed Behavior:

Mobs don't panic.

Expected Behavior:

Mobs would panic.