Merge pull request #454 from edx/feanil/pre_stage

Also don't run the edxapp restart handler when on workers.

playbooks/roles/edxapp/handlers/main.yml

@@ -5,7 +5,7 @@
     supervisorctl_path={{ supervisor_ctl }}
     config={{ supervisor_cfg }}
     name="edxapp:{{ item }}"
-  when: not devstack
+  when: celery_worker is not defined and not devstack
   sudo_user: "{{ supervisor_service_user }}"
   with_items: service_variants_enabled
   tags: deploy