worker failed on transient swift login exception

A worker died on a what looks like a transient exception:

2015-07-15 05:01:08,937 INFO:worker Putting results into swift autopkgtest-wily wily/amd64/p/plasma-framework/20150715_050108@
2015-07-15 05:01:08,942 INFO:connectionpool Starting new HTTP connection (1): 10.24.0.132
2015-07-15 05:01:38,946 ERROR:client Authorization Failure. Authorization Failed: Unable to establish connection to http://10.24.0.132:5000/v2.0/tokens
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/swiftclient/client.py", line 1181, in _retry
    self.url, self.token = self.get_auth()
  File "/usr/lib/python2.7/dist-packages/swiftclient/client.py", line 1155, in get_auth
    insecure=self.insecure)
  File "/usr/lib/python2.7/dist-packages/swiftclient/client.py", line 346, in get_auth
    insecure=insecure)
  File "/usr/lib/python2.7/dist-packages/swiftclient/client.py", line 283, in get_keystoneclient_2_0
    raise ClientException('Authorization Failure. %s' % err)
ClientException: Authorization Failure. Authorization Failed: Unable to establish connection to http://10.24.0.132:5000/v2.0/tokens
2015-07-15 05:01:38,950 INFO:connectionpool Starting new HTTP connection (1): 10.24.0.132
2015-07-15 05:02:08,954 ERROR:client Authorization Failure. Authorization Failed: Unable to establish connection to http://10.24.0.132:5000/v2.0/tokens
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/swiftclient/client.py", line 1181, in _retry
    self.url, self.token = self.get_auth()
  File "/usr/lib/python2.7/dist-packages/swiftclient/client.py", line 1155, in get_auth
    insecure=self.insecure)
  File "/usr/lib/python2.7/dist-packages/swiftclient/client.py", line 346, in get_auth
    insecure=insecure)
  File "/usr/lib/python2.7/dist-packages/swiftclient/client.py", line 283, in get_keystoneclient_2_0
    raise ClientException('Authorization Failure. %s' % err)
ClientException: Authorization Failure. Authorization Failed: Unable to establish connection to http://10.24.0.132:5000/v2.0/tokens
Traceback (most recent call last):
  File "/home/ubuntu/autopkgtest-cloud/worker/worker", line 305, in <module>
    main()
  File "/home/ubuntu/autopkgtest-cloud/worker/worker", line 293, in main
    queue.wait()
  File "/usr/lib/python2.7/dist-packages/amqplib/client_0_8/abstract_channel.py", line 97, in wait
    return self.dispatch_method(method_sig, args, content)
  File "/usr/lib/python2.7/dist-packages/amqplib/client_0_8/abstract_channel.py", line 117, in dispatch_method
    return amqp_method(self, args, content)
  File "/usr/lib/python2.7/dist-packages/amqplib/client_0_8/channel.py", line 2060, in _basic_deliver
    func(msg)
  File "/home/ubuntu/autopkgtest-cloud/worker/worker", line 188, in request
    swift_con.put_container(container, headers={'X-Container-Read': '.rlistings,.r:*'})
  File "/usr/lib/python2.7/dist-packages/swiftclient/client.py", line 1265, in put_container
    response_dict=response_dict)
  File "/usr/lib/python2.7/dist-packages/swiftclient/client.py", line 1181, in _retry
    self.url, self.token = self.get_auth()
  File "/usr/lib/python2.7/dist-packages/swiftclient/client.py", line 1155, in get_auth
    insecure=self.insecure)
  File "/usr/lib/python2.7/dist-packages/swiftclient/client.py", line 346, in get_auth
    insecure=insecure)
  File "/usr/lib/python2.7/dist-packages/swiftclient/client.py", line 283, in get_keystoneclient_2_0
    raise ClientException('Authorization Failure. %s' % err)
swiftclient.exceptions.ClientException: Authorization Failure. Authorization Failed: Unable to establish connection to http://10.24.0.132:5000/v2.0/tokens