cinder-scheduler fails if stevedore version < 0.8-2

cinder (and likely other openstack projects that use stevedore) fails to correctly load scheduling filters. Initially erroring as follows:

2013-04-16 14:19:27 ERROR [stevedore.extension] (stevedore 0.7.2 (/usr/lib/python2.7/dist-packages), Requirement.parse('stevedore>=0.8.0'))
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/stevedore/extension.py", line 75, in _load_plugins
    invoke_kwds,
  File "/usr/lib/python2.7/dist-packages/stevedore/extension.py", line 87, in _load_one_plugin
    plugin = ep.load()
  File "/usr/lib/python2.7/dist-packages/pkg_resources.py", line 1988, in load
    if require: self.require(env, installer)
  File "/usr/lib/python2.7/dist-packages/pkg_resources.py", line 2001, in require
    working_set.resolve(self.dist.requires(self.extras),env,installer))
  File "/usr/lib/python2.7/dist-packages/pkg_resources.py", line 588, in resolve
    raise VersionConflict(dist,req) # XXX put more info here
VersionConflict: (stevedore 0.7.2 (/usr/lib/python2.7/dist-packages), Requirement.parse('stevedore>=0.8.0'))

Later attempting to create + schedule volumes results in trace:

2013-04-16 15:02:45 ERROR [cinder.scheduler.manager] Failed to schedule_create_volume: Scheduler Host Filter AvailabilityZoneFilter, CapacityFilter, CapabilitiesFilter could not be found.
2013-04-16 15:02:45 ERROR [cinder.openstack.common.rpc.amqp] Exception during message handling
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/cinder/openstack/common/rpc/amqp.py", line 430, in _process_data
    rval = self.proxy.dispatch(ctxt, version, method, **args)
  File "/usr/lib/python2.7/dist-packages/cinder/openstack/common/rpc/dispatcher.py", line 133, in dispatch
    return getattr(proxyobj, method)(ctxt, **kwargs)
  File "/usr/lib/python2.7/dist-packages/cinder/scheduler/manager.py", line 115, in create_volume
    context, ex, request_spec)
  File "/usr/lib/python2.7/contextlib.py", line 24, in __exit__
    self.gen.next()
  File "/usr/lib/python2.7/dist-packages/cinder/scheduler/manager.py", line 104, in create_volume
    filter_properties)
  File "/usr/lib/python2.7/dist-packages/cinder/scheduler/filter_scheduler.py", line 67, in schedule_create_volume
    filter_properties)
  File "/usr/lib/python2.7/dist-packages/cinder/scheduler/filter_scheduler.py", line 204, in _schedule
    filter_properties)
  File "/usr/lib/python2.7/dist-packages/cinder/scheduler/host_manager.py", line 224, in get_filtered_hosts
    filter_classes = self._choose_host_filters(filter_class_names)
  File "/usr/lib/python2.7/dist-packages/cinder/scheduler/host_manager.py", line 191, in _choose_host_filters
    raise exception.SchedulerHostFilterNotFound(filter_name=msg)
SchedulerHostFilterNotFound: Scheduler Host Filter AvailabilityZoneFilter, CapacityFilter, CapabilitiesFilter could not be found.
2013-04-16 15:02:58 ERROR [cinder.scheduler.manager] Failed to schedule_create_volume: Scheduler Host Filter AvailabilityZoneFilter, CapacityFilter, CapabilitiesFilter could not be found.