When you summon a EntityHorse Variant 7,8 and so on and you kill them with kill @e[type=EntityHorse] the whole world turn red, because Minecraft will color the textures red (death) but it doesn't find any textures and it colors the whole world red 😃
Thanks to SethBling (Livestream)
Duplicate of MC-48954 - 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.