Snow Golems inside boats doesn't shoot at mobs

A Snow Golem placed in a boat doesn't shoot snowballs at other mobs. Whenever it spots a mob, it starts nodding rhythmically instead.

What I expected to happen was...:
The Snow Golems shooting snowballs at the Enderman.

What actually happened was...:
The Snow Golems started nodding.

Steps to Reproduce:
1. Summon a boat. (/summon Boat)
2. Summon a Snow Golem (or two if you want) at the same place to make it enter the boat. (/summon SnowMan)
3. Summon an Enderman within the shooting range of the summoned Snow Golem(s).
4. Done!