Function uncommitted 

pub fn uncommitted(repo: &Repo, dir: &Path) -> bool

Whether anything in this tree is missing from the commit, untracked files included.

review::snapshot asks only about tracked files, and the shape that matters here is a file the stand-alone pass wrote and never added: a new module a part needs to build is exactly that, and it would be pushed missing.

Public so that it can be tested against a real repository.