Zero-Downtime-Upgrade fails with `internal_addr_use_hostnames: true`

Hi,

when I set internal_addr_use_hostnames: true the zero-downtime-upgrade playbook does not work.

I need to add the following to the playbook start to make it working:

# Gather facts on all hosts but only if missing
- hosts: all:!gitlab_cluster:!ungrouped
  gather_facts: false
  tasks:
    - name: Gather Facts
      gather_facts:
      when: ansible_fqdn is not defined
      tags: always

The issue without the gather facts job is:

An exception occurred during task execution. To see the full traceback, use -vvv. The error was: ansible.errors.AnsibleUndefinedVariable: {{ haproxy_internal_int_addr }}: {{ (groups[haproxy_internal_primary_site_group_name] | sort | map('extract', hostvars, internal_addr_lookup) | join('')) if 'haproxy_internal' in groups else ''}}: 'ansible.vars.hostvars.HostVarsVars object' has no attribute 'ansible_fqdn'

Thanks in advance, Ron