Comment 1 for bug 1685226

Seeing this repeatedly in logs:

Traceback (most recent call last):\n', u' File "/usr/lib/python2.7/site-packages/nova/compute/manager.py", line 1783, in _do_build_and_run_instance\n filter_properties)\n', u' File "/usr/lib/python2.7/site-packages/nova/compute/manager.py", line 1981, in _build_and_run_instance\n instance_uuid=instance.uuid, reason=six.text_type(e))\n', u"RescheduledException: Build of instance a0f8fa09-d0dc-4652-883c-f8b533fc3aec was re-scheduled: local variable 'sibling_set' referenced before assignment\n