Specular Scale 0 on Light still affects Groom asset

When a light's Specular Scale is set to 0, the specular still affects hair / groom assets. The specular of other assets (like a shiny static mesh in the scene) is properly affected by the change. 

1. Place any groom asset in an empty scene
2. Place a light in the same scene
3. Set the light's "Specular Scale" to 0
4. The specular contribution is still apparent on the hair

The specular contribution change is effective on other assets, like a simple shiny cube in the scene.