Automatically set ci_testing flag

In the event of testing in the OpenStack CI system, we need to
operate differently with repositories as dependent changes may be
in other repositories.

playbooks/test-bifrost.yaml

@@ -5,8 +5,14 @@
   sudo: yes
   gather_facts: yes
   pre_tasks:
-    - set_fact: baremetal_csv_file="/tmp/baremetal.csv"
+    - name: "Set default baremetal.csv file if not already defined"
+      set_fact:
+         baremetal_csv_file: "/tmp/baremetal.csv"
       when: baremetal_csv_file is not defined
+    - name: "Set ci_testing flag if a list of changes are found in the environment variables"
+      set_fact:
+         ci_testing: true
+      when: lookup('env', 'ZUUL_CHANGES') != ""
   roles:
     - role: bifrost-create-vm-nodes
     - role: ironic-install