gate-tempest-dsvm-cells broken with cell v2 setup: "No hosts found to map to cell, exiting."

http://logs.openstack.org/98/316398/37/check/gate-tempest-dsvm-cells/61db698/logs/devstacklog.txt.gz#_2016-08-15_19_18_03_015

2016-08-15 19:18:03.015 | + lib/nova:create_cell:941 : nova-manage cell_v2 simple_cell_setup --transport-url rabbit://stackrabbit:secretrabbit@127.0.0.1:5672/
2016-08-15 19:18:05.858 | 2016-08-15 19:18:05.857 19005 DEBUG oslo_policy._cache_handler [req-51b31ef1-4087-49ae-b860-237770eae649 - -] Reloading cached file /etc/nova/policy.json read_cached_file /usr/local/lib/python2.7/dist-packages/oslo_policy/_cache_handler.py:38
2016-08-15 19:18:05.859 | 2016-08-15 19:18:05.859 19005 DEBUG oslo_policy.policy [req-51b31ef1-4087-49ae-b860-237770eae649 - -] Reloaded policy file: /etc/nova/policy.json _load_policy_file /usr/local/lib/python2.7/dist-packages/oslo_policy/policy.py:584
2016-08-15 19:18:06.089 | No hosts found to map to cell, exiting.

This also broke ironic.

http://logstash.openstack.org/#dashboard/file/logstash.json?query=message%3A%5C%22No%20hosts%20found%20to%20map%20to%20cell%2C%20exiting.%5C%22%20AND%20tags%3A%5C%22console%5C%22&from=7d

There is a revert here: https://review.openstack.org/#/c/355599/