britaniacraft/horsekeep — pull request #3 by AsaAyers (2014-07-22 04:02:21+00:00)
Title: Prevent summoning a horse from a different world

What do you think of this solution as far as supporting things like multiverse?

I have a multiverse server and I'd like to forbid people from bringing donkeys into creative and summoning them back to our survival world full of free stuff. This solves that problem without having to become dependent on multiverse.