Seems like the problem you're trying to address is that `os.path.relpath()` can accept either two `str` objects or two `bytes` objects, but not one of each. Is `root_rel_path` a `str` object or a `bytes` object? If you can ensure that `root_rel_path` is a `str`, then you should be able to also make sure that `git_diff_path` is always a `str`.