Dispensers cannot be used to heal iron golems

The Bug:

Dispensers cannot be used to heal iron golems.

Steps to Reproduce:

1. Build the setup as shown in the attachment below. setup.png
2. Stand on the diamond block and summon an iron golem with low health by using the command provided below.

   /summon minecraft:iron_golem ~ ~ ~ {Health:1f}

3. Place some iron ingots inside of the dispenser.
4. Activate the dispenser multiple times by using the lever, and watch the iron golem closely.
5. Take note as to whether or not dispensers can be used to heal iron golems.

Observed Behavior:

Dispensers cannot be used to heal iron golems.

Expected Behavior:

Dispensers would be able to be used to heal iron golems.