When building out the labtestn deployment the nova.conf config was kept as pristine as possible for rapid iteration. There are portions of the config that need to be ported from the nova-network version to ensure everything is ready to go. That could mean integrating the two templates with conditional statements or keeping them separate with a manual sync and testing. Since the nova-network template will be obsolete (and is rarely changed) the cleanest solution is probably to copy over any missing config and ensure it doesn't break things in the new context.
> ls modules/openstack/templates/mitaka/nova/common/**/*
modules/openstack/templates/mitaka/nova/common/neutron/api-paste.ini.erb
modules/openstack/templates/mitaka/nova/common/neutron/nova.conf.erb
modules/openstack/templates/mitaka/nova/common/nova_network/api-paste.ini.erb
modules/openstack/templates/mitaka/nova/common/nova_network/nova.conf.erb