I have a problem wit pragmatically finding get a GitDir for a given directory.
GitDir.fromExisting need the root dir or no dice.
GitDir.isGitDir returns true even on subdir of a git project. And i feel that is a bit inconsistent.

I would love one of the following:
GitDir.isGitRootDir(path)
GitDir.fromExisting works if you give it a sub directory of a git reposetory.
GitDir.findRoot(path).