CORD-536 updated to support the setting of repo via vars

Change-Id: I84988b634967d8be2e5a9f3a79352be5efa9c0c0
diff --git a/roles/head-node/tasks/main.yml b/roles/head-node/tasks/main.yml
index f85c86e..a6409ef 100644
--- a/roles/head-node/tasks/main.yml
+++ b/roles/head-node/tasks/main.yml
@@ -81,7 +81,7 @@
 - name: Ensure Compute and Switch Node Variables
   become: yes
   template:
-    src=files/compute-node-vars.yml
+    src=files/compute-node-vars.yml.j2
     dest=/etc/maas/ansible/vars/compute-node-vars.yml
     owner=maas
     group=maas