live-migrate error reporting raises errors itself

When trying nova live-migrate command without really knowing if it would work or not, the compute log shows this:

  from (pid=1803) to_xml /usr/lib/python2.7/dist-packages/nova/virt/libvirt/config.py:66
2013-01-25 15:30:02 ERROR nova.openstack.common.rpc.amqp [-] Exception during message handling
2013-01-25 15:30:02 TRACE nova.openstack.common.rpc.amqp Traceback (most recent call last):
2013-01-25 15:30:02 TRACE nova.openstack.common.rpc.amqp File "/usr/lib/python2.7/dist-packages/nova/openstack/common/rpc/amqp.py", line 275, in _process_data
2013-01-25 15:30:02 TRACE nova.openstack.common.rpc.amqp rval = self.proxy.dispatch(ctxt, version, method, **args)
2013-01-25 15:30:02 TRACE nova.openstack.common.rpc.amqp File "/usr/lib/python2.7/dist-packages/nova/openstack/common/rpc/dispatcher.py", line 145, in dispatch
2013-01-25 15:30:02 TRACE nova.openstack.common.rpc.amqp return getattr(proxyobj, method)(ctxt, **kwargs)
2013-01-25 15:30:02 TRACE nova.openstack.common.rpc.amqp File "/usr/lib/python2.7/dist-packages/nova/exception.py", line 117, in wrapped
2013-01-25 15:30:02 TRACE nova.openstack.common.rpc.amqp temp_level, payload)
2013-01-25 15:30:02 TRACE nova.openstack.common.rpc.amqp File "/usr/lib/python2.7/contextlib.py", line 24, in __exit__
2013-01-25 15:30:02 TRACE nova.openstack.common.rpc.amqp self.gen.next()
2013-01-25 15:30:02 TRACE nova.openstack.common.rpc.amqp File "/usr/lib/python2.7/dist-packages/nova/exception.py", line 92, in wrapped
2013-01-25 15:30:02 TRACE nova.openstack.common.rpc.amqp return f(*args, **kw)
2013-01-25 15:30:02 TRACE nova.openstack.common.rpc.amqp File "/usr/lib/python2.7/dist-packages/nova/compute/manager.py", line 2076, in check_can_live_migrate_destination
2013-01-25 15:30:02 TRACE nova.openstack.common.rpc.amqp instance, block_migration, disk_over_commit)
2013-01-25 15:30:02 TRACE nova.openstack.common.rpc.amqp File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/driver.py", line 2238, in check_can_live_migrate_destination
2013-01-25 15:30:02 TRACE nova.openstack.common.rpc.amqp self._compare_cpu(source_cpu_info)
2013-01-25 15:30:02 TRACE nova.openstack.common.rpc.amqp File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/driver.py", line 2366, in _compare_cpu
2013-01-25 15:30:02 TRACE nova.openstack.common.rpc.amqp LOG.error(reason=m % locals())
2013-01-25 15:30:02 TRACE nova.openstack.common.rpc.amqp TypeError: error() takes at least 2 arguments (1 given)
2013-01-25 15:30:02 TRACE nova.openstack.common.rpc.amqp
2013-01-25 15:30:02 ERROR nova.openstack.common.rpc.common [-] Returning exception error() takes at least 2 arguments (1 given) to caller
2013-01-25 15:30:02 ERROR nova.openstack.common.rpc.common [-] ['Traceback (most recent call last):\n', ' File "/usr/lib/python2.7/dist-packages/nova/openstack/common/rpc/amqp.py", line 275, in _process_data\n rval = self.proxy.dispatch(ctxt, version, method, **args)\n', ' File "/usr/lib/python2.7/dist-packages/nova/openstack/common/rpc/dispatcher.py", line 145, in dispatch\n return getattr(proxyobj, method)(ctxt, **kwargs)\n', ' File "/usr/lib/python2.7/dist-packages/nova/exception.py", line 117, in wrapped\n temp_level, payload)\n', ' File "/usr/lib/python2.7/contextlib.py", line 24, in __exit__\n self.gen.next()\n', ' File "/usr/lib/python2.7/dist-packages/nova/exception.py", line 92, in wrapped\n return f(*args, **kw)\n', ' File "/usr/lib/python2.7/dist-packages/nova/compute/manager.py", line 2076, in check_can_live_migrate_destination\n instance, block_migration, disk_over_commit)\n', ' File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/driver.py", line 2238, in check_can_live_migrate_destination\n self._compare_cpu(source_cpu_info)\n', ' File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/driver.py", line 2366, in _compare_cpu\n LOG.error(reason=m % locals())\n', 'TypeError: error() takes at least 2 arguments (1 given)\n']

Which suggests that the error logging itself raises an exception?