I tried to open the MAAS URL, and received "The server encountered an internal error..."

Looking at /var/log/apache2/error.log I see the following python backtrace:

[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] mod_wsgi (pid=1456): Target WSGI script '/usr/share/maas/wsgi.py' cannot be loaded as Python module.
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] mod_wsgi (pid=1456): Exception occurred processing WSGI script '/usr/share/maas/wsgi.py'.
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] Traceback (most recent call last):
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] File "/usr/share/maas/wsgi.py", line 30, in <module>
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] start_up()
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] File "/usr/lib/python2.7/dist-packages/maasserver/start_up.py", line 59, in start_up
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] inner_start_up()
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] File "/usr/lib/python2.7/dist-packages/maasserver/start_up.py", line 87, in inner_start_up
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] write_full_dns_config(reload_retry=True)
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] File "/usr/lib/python2.7/dist-packages/maasserver/dns.py", line 309, in write_full_dns_config
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] args=[['reload'], reload_retry]))
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] File "/usr/lib/python2.7/dist-packages/celery/app/task/__init__.py", line 353, in delay
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] return self.apply_async(args, kwargs)
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] File "/usr/lib/python2.7/dist-packages/celery/app/task/__init__.py", line 449, in apply_async
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] publish = publisher or self.app.amqp.publisher_pool.acquire(block=True)
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] File "/usr/lib/python2.7/dist-packages/kombu/connection.py", line 657, in acquire
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] R = self.prepare(R)
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] File "/usr/lib/python2.7/dist-packages/kombu/pools.py", line 54, in prepare
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] p = p()
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] File "/usr/lib/python2.7/dist-packages/kombu/pools.py", line 45, in <lambda>
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] return lambda: self.create_producer()
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] File "/usr/lib/python2.7/dist-packages/celery/app/amqp.py", line 265, in create_producer
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] pub = self.app.amqp.TaskPublisher(conn, auto_declare=False)
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] File "/usr/lib/python2.7/dist-packages/celery/app/amqp.py", line 328, in TaskPublisher
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] return TaskPublisher(*args, **self.app.merge(defaults, kwargs))
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] File "/usr/lib/python2.7/dist-packages/celery/app/amqp.py", line 158, in __init__
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] super(TaskPublisher, self).__init__(*args, **kwargs)
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] File "/usr/lib/python2.7/dist-packages/kombu/compat.py", line 61, in __init__
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] super(Publisher, self).__init__(connection, self.exchange, **kwargs)
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] File "/usr/lib/python2.7/dist-packages/kombu/messaging.py", line 79, in __init__
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] self.revive(self.channel)
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] File "/usr/lib/python2.7/dist-packages/kombu/messaging.py", line 168, in revive
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] channel = channel.default_channel
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] File "/usr/lib/python2.7/dist-packages/kombu/connection.py", line 581, in default_channel
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] self.connection
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] File "/usr/lib/python2.7/dist-packages/kombu/connection.py", line 574, in connection
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] self._connection = self._establish_connection()
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] File "/usr/lib/python2.7/dist-packages/kombu/connection.py", line 533, in _establish_connection
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] conn = self.transport.establish_connection()
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] File "/usr/lib/python2.7/dist-packages/kombu/transport/amqplib.py", line 279, in establish_connection
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] connect_timeout=conninfo.connect_timeout)
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] File "/usr/lib/python2.7/dist-packages/kombu/transport/amqplib.py", line 89, in __init__
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] super(Connection, self).__init__(*args, **kwargs)
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] File "/usr/lib/python2.7/dist-packages/amqplib/client_0_8/connection.py", line 144, in __init__
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] (10, 30), # tune
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] File "/usr/lib/python2.7/dist-packages/amqplib/client_0_8/abstract_channel.py", line 95, in wait
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] self.channel_id, allowed_methods)
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] File "/usr/lib/python2.7/dist-packages/amqplib/client_0_8/connection.py", line 202, in _wait_method
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] self.method_reader.read_method()
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] File "/usr/lib/python2.7/dist-packages/amqplib/client_0_8/method_framing.py", line 221, in read_method
[Sat Oct 13 19:44:13 2012] [error] [client 127.0.0.1] raise m