undercloud-prep-containers.sh is run on stable/newton jobs

[Attila Darazs]

http://logs.openstack.org/16/542816/4/check/tripleo-ci-centos-7-undercloud-oooq/31cf4f9/logs/undercloud/home/zuul/undercloud_prep_containers.log.txt.gz

This job should not attempt to prepare the containers as it is run on newton branch.

It looks like containerized_undercloud is true, which should not happen in this job.

https://github.com/openstack/tripleo-quickstart-extras/blob/5aaebadbe166f478bcd917f69ea19e647390e52d/roles/undercloud-deploy/tasks/main.yml#L24

[Sergii Golovatiuk (sgolovatiuk)]

https://review.openstack.org/#/c/543893/ fixes this