
In the case the containers list was empty or non existent, container-check would explode and produce a traceback. This is for example visible at [1]. This commit makes container-check more robust about the input data. [1] http://logs.openstack.org/06/572806/1/experimental/tripleo-ci-centos-7-scenario009-multinode-oooq/a88c395/logs/undercloud/home/zuul/overcloud_prep_containers.log.txt.gz Change-Id: I5639cd2b0b32b8f1261064ee178193f0c589f233