Neovim.app isn't in Homebrew. Are you referring to its dependencies like scons, msgpack-c, or something else?

What is failing?

It builds fine for me just now on 10.10. I did have to pop in to zsh instead of fish because of `SyntaxError: Missing parentheses in call to 'print'` though. The font rendering looks a bit off for me but it's blazingly fast.

I was having trouble building the neovim package, but I did not realize that I did not have the latest command-line tools. Updating those fixed the issue.