I think it's something made outside Disney that they picked up for distribution by them.
True. I've seen it a few times. It was released theatrically in the UK (and in the US for about five minutes) as The Wind in the Willows, and Disney grabbed the distribution rights for video and changed the title.
A couple of Pythons are in it, most notably Terry Jones in the lead. It has some interesting elements - the makeup and music, in particular - but it's quite dark, and has neither the sweetness of Grahame's original work nor the whimsy and energy of the Disney. Neither fish nor fowl. A curio at best, IMHO.