Merge pull request #3334 from holta/avoid-iiab.ini-pollution

detected_network.yml: Disallow multi-line var second_gateway_found ~= exclude_devices (to avoid polluting /etc/iiab/iiab.ini)

roles/network/tasks/detected_network.yml

@@ -142,6 +142,11 @@
   register: second_gateway_found
   changed_when: False
 
+- name: If multiple secondary gateways are detected, fail intentionally and explain
+  fail:
+    msg: "IIAB currently DOES NOT SUPPORT multiple secondary gateways: {{ second_gateway_found.stdout }}"
+  when: second_gateway_found.stdout_lines is defined and second_gateway_found.stdout_lines | length > 1
+
 - name: Set exclude_devices if default gateway has been detected for {{ second_gateway_found.stdout }}
   set_fact:
     exclude_devices: "{{ second_gateway_found.stdout }}"