Put this bit of clever back because it doesn't work when you un-jinja this.

playbooks/roles/common/tasks/main.yml

@@ -2,7 +2,7 @@
 - name: Check Configuration Sources
   fail:
     msg: "Configuration Sources Checking (COMMON_EXTRA_CONFIGURATION_SOURCES_CHECKING) is enabled, you must define {{ item }}"
-  when: COMMON_EXTRA_CONFIGURATION_SOURCES_CHECKING and (item is not defined or item != True)
+  when: COMMON_EXTRA_CONFIGURATION_SOURCES_CHECKING and ({{ item }} is not defined or {{ item }} != True)
   with_items: "{{ COMMON_EXTRA_CONFIGURATION_SOURCES }}"
   tags:
     - "install"