Regarding Horses

Soo... I was taming a horse. I put some diamond horse armor on it.

What I expected to happen was...:
I thought it would just tame the horse, and it did.

What actually happened was...:
I got the "Complete Catalog" advancement. When I put the diamond horse armor on it, the horse was invisible.

Steps to Reproduce:
1. Tame a horse. You get glitch A.
2. Put diamond horse armor on it. You get glitch B.
3. Aaand then you have an invisible horse and a random advancement. Good job!