Is there a CoffeeScript fork with no changes other than fixed scoping, so that it's largely compatible with CoffeeScript (completely compatible if the code has no outer-variable assignments)? I'd consider acceptable ways to assign an outer variable to include := a la LiveScript, or nonlocal a la Python, or something else.
There's not. I think LiveScript is compatible with CoffeeScript, but that isn't anything near "a small patch".