def unpack_directory(filename, extract_dir, progress_filter=default_filter):
    """ "Unpack" a directory, using the same interface as for archives

    Raises ``UnrecognizedFormat`` if `filename` is not a directory
    """
    if not os.path.isdir(filename):
        raise UnrecognizedFormat("%s is not a directory" % filename)

    paths = {
        filename: ('', extract_dir),
    }
    for base, dirs, files in os.walk(filename):
        src, dst = paths[base]
        for d in dirs:
            paths[os.path.join(base, d)] = src + d + '/', os.path.join(dst, d)
        for f in files:
            target = os.path.join(dst, f)
            target = progress_filter(src + f, target)
            if not target:
                # skip non-files
                continue
            ensure_directory(target)
            f = os.path.join(base, f)
            shutil.copyfile(f, target)
            shutil.copystat(f, target)
 "Unpack" a directory, using the same interface as for archives

    Raises ``UnrecognizedFormat`` if `filename` is not a directory
    
product/gradle-plugin/src/main/python/setuptools/archive_util.py