Add undefined variables check

roles/openshift_master/handlers/main.yml

@@ -6,7 +6,7 @@
   when:
   - not (master_api_service_status_changed | default(false) | bool)
   - openshift.master.cluster_method == 'native'
-  - master_api_enabled.rc == 0 or openshift_version | version_compare('3.7','>=')
+  - master_api_enabled is defined and (master_api_enabled.rc == 0 or openshift_version | version_compare('3.7','>='))
   notify:
   - Verify API Server
 
@@ -20,7 +20,7 @@
   when:
   - not (master_controllers_service_status_changed | default(false) | bool)
   - openshift.master.cluster_method == 'native'
-  - master_controllers_enabled.rc == 0 or openshift_version | version_compare('3.7','>=')
+  - master_controllers_enabled is defined and (master_controllers_enabled.rc == 0 or openshift_version | version_compare('3.7','>='))
 
 # For now, this handler is called only from update_etcd_client_urls.yml in case migration from previous version.
 # Thus, {{ *_service_status_changed }} like api, controllers is neither implemented nor handled.
@@ -29,7 +29,7 @@
     name: "{{ openshift.common.service_type }}-master"
     state: restarted
   when:
-  - single_master_enabled.rc == 0 or openshift_version | version_compare('3.7','<')
+  - single_master_enabled is defined and (single_master_enabled.rc == 0 or openshift_version | version_compare('3.7','<'))
   notify:
   - Verify API Server