I would recommend GitPython which is full featured, very well documented and easy to use IMO. For more info, check out this answer

for item in repo.index.diff(None):
    print(item.a_path)

or to get just the list:

changedFiles = [item.a_path for item in repo.index.diff(None)]

repo.index.diff() returns git.diff.Diffable described in http://gitpython.readthedocs.io/en/stable/reference.html#module-git.diff

So the function can look like this:

def get_status(repo, path):
    changed = [item.a_path for item in repo.index.diff(None)]
    if path in repo.untracked_files:
        return "untracked"
    elif path in changed:
        return "modified"
    else:
        return "don't care"

See https://stackoverflow.com/a/15862203/197789

E.g.

commits_behind = repo.iter_commits('master..origin/master')

and

commits_ahead = repo.iter_commits('origin/master..master')

Then you can use something like the following to go from iterator to a count:

count = sum(1 for c in commits_ahead)

(You may want to fetch from the remotes before running iter_commits, eg: repo.remotes.origin.fetch())

This was last checked with GitPython 1.0.2.