branding: fix variable checking

branding/tasks/main.yml

@@ -8,7 +8,9 @@
     owner: root
     group: root
     mode: 0644
-  when: branding_motd
+  when:
+    - branding_motd is defined
+    - branding_motd != ""
   tags:
     - branding
     - shell
@@ -20,7 +22,9 @@
     owner: root
     group: root
     mode: 0644
-  when: branding_issuenet
+  when:
+    - branding_issuenet is defined
+    - branding_issuenet != ""
   tags:
     - branding
     - shell