Checked with 3.4.0 alpha, works fine. Apart from the tests mentioned, I used the following script to check digest auth:

    from urllib import request

    url = 'http://httpbin.org/digest-auth/auth/user/passwd'
    req = request.Request(url)

    password_manager = request.HTTPPasswordMgrWithDefaultRealm()
    password_manager.add_password(None, url, 'user', 'passwd')

    auth_manager = request.HTTPDigestAuthHandler(password_manager)
    opener = request.build_opener(auth_manager)

    request.install_opener(opener)
    handler = request.urlopen(req)

    assert handler.getcode() == 200