dynamic inventory bug when group exists but its empty

roles/openshift_storage_glusterfs/tasks/glusterfs_registry.yml

@@ -48,7 +48,7 @@
     glusterfs_heketi_ssh_sudo: "{{ openshift_storage_glusterfs_registry_heketi_ssh_sudo | bool }}"
     glusterfs_heketi_ssh_keyfile: "{{ openshift_storage_glusterfs_registry_heketi_ssh_keyfile }}"
     glusterfs_heketi_fstab: "{{ openshift_storage_glusterfs_registry_heketi_fstab }}"
-    glusterfs_nodes: "{% if groups.glusterfs_registry is defined %}{% set nodes = groups.glusterfs_registry %}{% elif 'groups.glusterfs' is defined %}{% set nodes = groups.glusterfs %}{% else %}{% set nodes = '[]' %}{% endif %}{{ nodes }}"
+    glusterfs_nodes: "{% if groups.glusterfs_registry is defined and groups['glusterfs_registry'] | length > 0 %}{% set nodes = groups.glusterfs_registry %}{% elif 'groups.glusterfs' is defined and groups['glusterfs'] | length > 0 %}{% set nodes = groups.glusterfs %}{% else %}{% set nodes = '[]' %}{% endif %}{{ nodes }}"
 
 - include_tasks: glusterfs_common.yml
   when: