基本的HTTP身份验证，扭曲不起作用

Question

我有以下代码：

import sys

from zope.interface import implementer

from twisted.python import log
from twisted.internet import reactor
from twisted.web import server, resource, guard
from twisted.cred.portal import IRealm, Portal
from twisted.cred.checkers import InMemoryUsernamePasswordDatabaseDontUse


class GuardedResource(resource.Resource):
    """
    A resource which is protected by guard and requires authentication in order
    to access.
    """
    def getChild(self, path, request):
        return self


    def render(self, request):
        return "Authorized!"



@implementer(IRealm)
class SimpleRealm(object):
    """
    A realm which gives out L{GuardedResource} instances for authenticated
    users.
    """

    def requestAvatar(self, avatarId, mind, *interfaces):
        if resource.IResource in interfaces:
            return resource.IResource, GuardedResource(), lambda: None
        raise NotImplementedError()

def main():
    log.startLogging(sys.stdout)
    checkers = [InMemoryUsernamePasswordDatabaseDontUse(joe='blow')]
    portal = Portal(SimpleRealm(), checkers)

    resource = guard.HTTPAuthSessionWrapper(portal, [guard.BasicCredentialFactory('auth')])

    reactor.listenTCP(8889, server.Site(resource = resource))
    reactor.run()

if __name__ == '__main__':
    main()

当我们启动服务器并访问URL时：http://localhost:8889/弹出提示，要求我们输入用户名和密码。输入user = joe和password = blow后，我们仍然无权访问该网站。上面的代码有什么问题以及如何解决？