def METHOD_NAME():
    result = set()
    try:
        output = check_output(["git", "diff", "--stat", "--name-only", "@{upstream}"])
    except NuitkaCalledProcessError:
        return result
    for line in output.splitlines():
        if str is not bytes:
            line = line.decode("utf8")
        # Removed files appear too, but are useless to talk about.
        if not os.path.exists(line):
            continue
        result.add(line)
    return tuple(sorted(result))