def find_path_to_setup_from_repo_root(location, repo_root):
    # type: (str, str) -> Optional[str]
    """
    Find the path to `setup.py` by searching up the filesystem from `location`.
    Return the path to `setup.py` relative to `repo_root`.
    Return None if `setup.py` is in `repo_root` or cannot be found.
    """
    # find setup.py
    orig_location = location
    while not os.path.exists(os.path.join(location, 'setup.py')):
        last_location = location
        location = os.path.dirname(location)
        if location == last_location:
            # We've traversed up to the root of the filesystem without
            # finding setup.py
            logger.warning(
                "Could not find setup.py for directory %s (tried all "
                "parent directories)",
                orig_location,
            )
            return None

    if samefile(repo_root, location):
        return None

    return os.path.relpath(location, repo_root)

    Find the path to `setup.py` by searching up the filesystem from `location`.
    Return the path to `setup.py` relative to `repo_root`.
    Return None if `setup.py` is in `repo_root` or cannot be found.
    
product/gradle-plugin/src/main/python/pip/_internal/vcs/versioncontrol.py