Spotted this video on YouTube while I was searching for some Fleetwood Mac live performances of "The Green Manalishi":
https://www.youtube.com/watch?v=IoSxo6eJCho
It's Nirvana in September 1991, playing at a record/video store appearance just a week after "Smells Like Teen Spirit" was released and a week before the release of the "Nevermind" album. Krist Novoselic and Dave Grohl are playing around while Kurt Cobain switches to a new guitar and tunes up. Krist breaks into a very sloppy "The Green Manalishi", singing some of the lyrics. I'm guessing he learned it from the Judas Priest cover version rather than the original but who knows?
There's another video on YouTube of this same in-store appearance - that one has better video quality but this one shows what's going on much better.