populate the default user variables file

The user_variables file may be empty. If it is, some older
versions of OSA will break. This new task simply ensures the variable
file is populated which will help us build and test more versions of OSA
as needed.

Change-Id: I38d204b41f781fe303d145878dfdbaa8172e16ba
Signed-off-by: Kevin Carter <kevin.carter@rackspace.com>

multi-node-aio/playbooks/deploy-osa.yml

@@ -86,6 +86,16 @@
       when:
         - pre_config_osa | default(true) | bool
 
+    - name: Ensure the user_variables file is populated
+      lineinfile:
+        path: /etc/openstack_deploy/user_variables.yml
+        regexp: '^{{ item }}'
+        line: '{{ item }}'
+        create: yes
+      with_items:
+        - '---'
+        - 'osa_ops_mnaio: true'
+
     - name: Bootstrap ansible
       command: bash ./scripts/bootstrap-ansible.sh
       args: