bugfix: update default home directory

[zhan9san]

If there is no customized _common_config_dir defined, it will raise an error, FAILED! => {"changed": false, "msg": "useradd: invalid home directory ''\n", "name": "foo", "rc": 3}.

Here is an Minimal reproducible example

Playbook

- hosts: ubuntu
  become: true
  vars:
    _common_system_user: foo
    _common_system_group: foo
    _common_config_dir: ""

  tasks:
    - name: "Create system group {{ _common_system_group }}"
      ansible.builtin.group:
        name: "{{ _common_system_group }}"
        system: true
        state: present
      become: true

    - name: "Create system user {{ _common_system_user }}"
      ansible.builtin.user:
        name: "{{ _common_system_user }}"
        system: true
        shell: "/usr/sbin/nologin"
        group: "{{ _common_system_group }}"
        home: "{{ _common_config_dir | default('/') }}"
        create_home: false
      become: true

Result

❯ ansible-playbook -i invenotory.yaml test.yaml
PLAY [ubuntu] ***************************************************************************************************************************************************************************************************

TASK [Gathering Facts] ****************************************************************************************************************************************************************************************************
ok: [ubuntu]

TASK [Create system group foo] ********************************************************************************************************************************************************************************************
ok: [ubuntu]

TASK [Create system user foo] *********************************************************************************************************************************************************************************************
fatal: [ubuntu]: FAILED! => {"changed": false, "msg": "useradd: invalid home directory ''\n", "name": "foo", "rc": 3}

PLAY RECAP ****************************************************************************************************************************************************************************************************************
ubuntu          : ok=2    changed=0    unreachable=0    failed=1    skipped=0    rescued=0    ignored=0   

[gardar]

LGTM, thanks!