That would definitely take the sting out of that permanent redirect. But I am still wondering why we redirect at all. Why not leave redirects to the user and do:

if os.path.isdir(path):
    if not path.endswith('/'):
        path = path + '/'
    for index in "index.html", "index.htm":
        index = os.path.join(path, index)
        if os.path.exists(index):
            path = index
            break