Ansible append an existing list using set_fact

determine_target.yml

---
- name: Set facts on all nodes
  hosts: "{{cli_hosts}}"
  gather_facts: false
  tasks:
    - name: determine current target
      stat: path=/etc/current
      register: current_link

    - set_fact:
        target: "{{ current_link.stat.lnk_source|basename }}"

    - debug: var=target


- name: Loop through facts and process them
  hosts: localhost
  gather_facts: false
  tasks:
    - command: mktemp
      register: temp_file

    - template: src=targets.yml.j2 dest="{{ temp_file.stdout }}"

    - include_vars: "{{ temp_file.stdout }}"

    - file: path="{{ temp_file.stdout }}" state=absent

    - debug: var=final_targets

targets.yml.j2

---
final_targets:
{% for host in hostvars %}
{% if 'target' in hostvars[host] %}
 - {{ hostvars[host]['target'] }}
{% endif %}
{% endfor %}