make known_hosts idempotent for OOD login host

Author: sjpb

ansible/roles/openondemand/tasks/main.yml

@@ -139,7 +139,7 @@
   blockinfile:
     path: /etc/ssh/ssh_known_hosts
     create: true
-    block: "{{ _openondemand_login_key.stdout }}"
+    block: "{{ _openondemand_login_key.stdout_lines | sort | join('\n') }}"
     marker: "# {mark} ANSIBLE MANGED BLOCK: openondemand login host" # allows other tasks to use blockinfile on this file
     owner: root
     group: root