I tamed a horse and gave it diamond armor, then I gave it the new SkeletonTrap tag and set it to 1b (Using /entitydata @e[type=EntityHorse,c=1]

). As expected, the horse turned into 4 skeleton horses, but one of them had a white texture and when you open its inventory, you can see the diamond horse item but it's in no slot and doesn't show up its name. You can also take it out, but the texture of the horse still stays white.