Basically if you use a potion of invisibility on a player or mob with armor, that player or mob would still show the armor. When you use it on a horse, the armor takes the effect.
MC-35246
Horse armor goes invisible with horse
Resolved
Duplicate
0
user-c60ef
(Unassigned)
Unconfirmed
Minecraft 1.6.2, Minecraft 1.6.4, Minecraft 13w39b, Minecraft 13w41b
Retrieved
Duplicate of MC-13738 - If you have not, please use the search function in the future, to see if your bug has already been submitted. If you could not find the original report, please comment with the keywords you searched for.