access: fix parsing of existing switch VLANs

If ansible won’t handle edge cases then we must.

roles/access/tasks/main.yml

@@ -18,8 +18,9 @@
 # Determine VLANs to add and remove from switch.
 - set_fact:
     actual_vlans: "{{ vlans | map(attribute='vid') }}"
-    switch_vlans: "{{ ansible_net_config | split('\n') | select('match', '^ *vlan (range )?[0-9]')
-        | map('regex_search', '[0-9,-]+') | join(',') | ansible.netcommon.vlan_expander }}"
+    switch_vlans: "{{ ansible_net_config | split('\n')
+        | select('match', '^ *vlan (range )?[0-9]') | map('regex_search', '[0-9,-]+') | join(',')
+        | default('0', true) |  ansible.netcommon.vlan_expander | reject('eq', 0) }}" # vlan_expander barfs on empty string so add/remove a fake VLAN 0
 
 - set_fact:
     add_vlans: "{{ actual_vlans | difference(switch_vlans) }}"