avoid unnecessary failure to delete a list of empty workflows
avoid unnecessary failure to delete a list of empty workflows

Improved execution output by avoiding confusing errors.

Change-Id: I2b6b03b6ff0178564a21f6b3c8578ac2d5f19023

openstack/tripleo-heat-templates,openstack/tripleo-heat-templates,dprince/tripleo-heat-templates,dprince/tripleo-heat-templates