cinder_volume_node_names is not defined

During an update R->S the following behaviour is observed.

openstack overcloud upgrade prepare --templates \
  -e /home/stack/containers-prepare-parameter.OVS.yaml \
  -e /home/stack/templates/node-info.yaml \
  -r /home/stack/STEIN_Roles_data.yaml \
  -n /home/stack/STEINtemplates/network_data.yaml \
  -e /home/stack/STEINtemplates/network-environment.yaml \
  -e /home/stack/STEINtemplates/environments/network-isolation.yaml \
  -e /home/stack/STEINtemplates/environments/ceph-ansible/ceph-ansible-external.yaml \
  -e /home/stack/STEINtemplates/environments/updates/update-from-ml2-ovs-from-rocky.yaml \
  -e /home/stack/STEINtemplates/ceph-config.yaml \
  -e /home/stack/STEINtemplates/environments/docker.yaml \
  -e /home/stack/STEINtemplates/environments/docker-ha.yaml \
  -e /usr/share/openstack-tripleo-heat-templates/environments/services/mistral.yaml \
  -e /home/stack/STEINtemplates/environments/ssl/enable-tls.yaml \
  -e /home/stack/STEINtemplates/environments/ssl/inject-trust-anchor.yaml \
  -e /home/stack/STEINtemplates/environments/ssl/tls-endpoints-public-dns.yaml \
  -e /home/stack/templates/cloudname.yaml \
  -e /home/stack/STEINtemplates/environments/neutron-ovs-dvr.yaml \
  -e /home/stack/updaterepos.yaml \

ran fine

openstack overcloud external-update run --tags container_image_prepare ran fine

openstack overcloud upgrade run --limit overcloud- Controller-0 --playbook upgrade_steps_playbook.yaml Failed with cinder_volume_node_names is undefinded in ansible

After digging a bit I saw that

https://github.com/openstack/tripleo-heat-templates/blob/master/deployment/cinder/cinder-volume-pacemaker-puppet.yaml#L348

and https://github.com/openstack/tripleo-heat-templates/blob/stable/stein/deployment/cinder/cinder-volume-pacemaker-puppet.yaml#L350

Are a bit different. I.e. there is a default empty variable which exists on master as part of https://github.com/openstack/tripleo-heat-templates/commit/b0e70081968c96af04d2858d040f97a67115391f but has not been backported on the other branches.

Should it be ?
If not, where is cinder_volume_node_names defined cause I cannot find it in THT or on facter on the controllers.

Logs & Configs
==============

Cinder volume service running with ceph Backend.
ansible-2.8.6-1.el7.noarch

http://paste.openstack.org/show/793062/