Transient error /w MAAS provider: Unknown operation: 'list_allocated'.

I've seen this with my own eyes once in the last couple of days when running 'juju status' but it seems to be happening sporadically in our scripted deployments.

After deploying a bunch of services, waiting for them to hit 'started' state, and adding a number of relations, I've noticed this in our logs:

2012-07-06 13:32:40,953 INFO Connecting to environment...
2012-07-06 13:32:41,781 INFO Connected to environment.
2012-07-06 13:32:42,055 INFO Added mysql-shared relation to all service units.
2012-07-06 13:32:42,055 INFO 'add_relation' command finished successfully
2012-07-06 13:32:47,432 INFO Connecting to environment...
2012-07-06 13:32:47,738 ERROR Cannot connect to environment: Unknown operation: 'list_allocated'.
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/juju/providers/common/connect.py", line 42, in run
    client = yield self._internal_connect(share)
  File "/usr/lib/python2.7/dist-packages/twisted/internet/defer.py", line 1037, in _inlineCallbacks
    result = result.throwExceptionIntoGenerator(g)
  File "/usr/lib/python2.7/dist-packages/twisted/python/failure.py", line 382, in throwExceptionIntoGenerator
    return g.throw(self.type, self.value, self.tb)
  File "/usr/lib/python2.7/dist-packages/juju/providers/common/connect.py", line 58, in _internal_connect
    candidates = yield self._provider.get_zookeeper_machines()
  File "/usr/lib/python2.7/dist-packages/twisted/internet/defer.py", line 1037, in _inlineCallbacks
    result = result.throwExceptionIntoGenerator(g)
  File "/usr/lib/python2.7/dist-packages/twisted/python/failure.py", line 382, in throwExceptionIntoGenerator
    return g.throw(self.type, self.value, self.tb)
  File "/usr/lib/python2.7/dist-packages/juju/providers/common/findzookeepers.py", line 32, in find_zookeepers
    machine = yield provider.get_machine(instance_id)
  File "/usr/lib/python2.7/dist-packages/twisted/internet/defer.py", line 1037, in _inlineCallbacks
    result = result.throwExceptionIntoGenerator(g)
  File "/usr/lib/python2.7/dist-packages/twisted/python/failure.py", line 382, in throwExceptionIntoGenerator
    return g.throw(self.type, self.value, self.tb)
  File "/usr/lib/python2.7/dist-packages/juju/providers/maas/provider.py", line 91, in get_machines
    instances = yield self.maas_client.get_nodes(instance_ids)
  File "/usr/lib/python2.7/dist-packages/twisted/internet/defer.py", line 545, in _runCallbacks
    current.result = callback(current.result, *args, **kw)
  File "/usr/lib/python2.7/dist-packages/juju/providers/maas/maas.py", line 69, in _process_error
    raise ProviderError(error.response)
ProviderError: Unknown operation: 'list_allocated'.
2012-07-06 13:32:47,739 ERROR Unknown operation: 'list_allocated'.
2012-07-06 13:32:53,109 INFO Connecting to environment...
2012-07-06 13:32:53,927 INFO Connected to environment.
2012-07-06 13:32:54,159 INFO Added rabbitmq relation to all service units.
2012-07-06 13:32:54,159 INFO 'add_relation' command finished successfully
2012-07-06 13:32:59,545 INFO Connecting to environment...

In this case, the mysql relation is the first of many to be added. The others seem to be added fine. I'm unsure where to look in MAAS's logfiles for any relevant traces on that end.

I've also been experiencing transient errors deploying services, though I'm not certain it is the same issue. I will update here if it turns out the same traceback is popping up around those failures.