standalone deployment failure on f28 with unable to find user root:

[Sorin Sbarnea]

error mounting image volumes: unable to find user root: no matching entries in passwd file

-- Failed running docker-puppet.py for swift",
-- b'error mounting image volumes: unable to find user root: no matching entries in passwd file\\n'",

See: http://logs.openstack.org/46/620146/3/check/tripleo-ci-fedora-28-standalone/c0e5eac/logs/undercloud/home/zuul/standalone_deploy.log.txt.gz#_2018-11-27_11_47_05
LogStash: http://logstash.openstack.org/#dashboard/file/logstash.json?query=message%3A%5C%22error%20mounting%20image%20volumes%3A%20unable%20to%20find%20user%20root%3A%20no%20matching%20entries%20in%20passwd%20file%5C%22