common.get_networks_for_instance causes 'NoneType' object is unsubscriptable when using ipv6

[Dan Prince]

Seeing the following TypeErrors from nova-api.log when trying to create servers:

(nova.api.openstack.wsgi): TRACE: File "/usr/lib/pymodules/python2.6/nova/api/openstack/common.py", in get_networks_for_instance
(nova.api.openstack.wsgi): TRACE: ipv6_addr = ipv6.to_global(cidr_v6, vif['address'],
(nova.api.openstack.wsgi): TRACE: TypeError: 'NoneType' object is unsubscriptable

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This causes HTTP 404 errors to be returned to the client when the request should have actually succeeded.

[Mark Washenberger (markwash)]

This looks like it was probably already fixed in [Change-Id: I37d21105d6306f0a812c5eb0f0717a5094cd17b9] because from that we have in common.py:

306 network = fixed_ip['network']
307 vif = fixed_ip.get('virtual_interface')
308 if not network or not vif:
309 name = instance['name']
310 ip = fixed_ip['address']
311 LOG.warn(_("Instance %(name)s has stale IP "
312 "address: %(ip)s (no network or vif)") % locals())
313 continue

Perhaps there is still an underlying problem (why is vif == None?) but I expect this would prevent it from showing up as a 404 or 500 error.

[Mark Washenberger (markwash)]

Fairly certain this is fixed in https://review.openstack.org/#change,1123