##### SUMMARY

The merge of #45507 broke `update_password="on_create"` on Alpine Linux with the shadow package installed.

This does not work anymore
```yml
  - name: add users                                                                                                                                                                                                                                  
    user:
      name: "{{ item.name }}"
      comment: "{ item.comment }}"
      shell: "/bin/zsh"
      password: '*'
      update_password: on_create
   with_items:
    ....
```

After the PR, all users that have a password that is not '*' will get their password changed.

Reverting bf3e397ea7922e8bd8b8ffbc05d1aede0317d119, makes 'update_password: on_create' work as expected again.

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
<!--- Write the short name of the module, plugin, task or feature below, use your best guess if unsure -->

lib/ansible/modules/system/user.py

##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```paste below
2.8.7
```

##### CONFIGURATION
<!--- Paste verbatim output from "ansible-config dump --only-changed" between quotes -->
```paste below

```

##### OS / ENVIRONMENT
<!--- Provide all relevant information below, e.g. target OS versions, network device firmware, etc. -->

Alpine Linux

##### STEPS TO REPRODUCE
<!--- Describe exactly how to reproduce the problem, using a minimal test-case -->

<!--- Paste example playbooks or commands between quotes below -->
```yaml
  - name: add users                                                                                                                                                                                                                                  
    user:
      name: "{{ item.name }}"
      comment: "{ item.comment }}"
      shell: "/bin/zsh"
      password: '*'
      update_password: on_create
```

<!--- HINT: You can paste gist.github.com links for larger files -->

##### EXPECTED RESULTS
<!--- Describe what you expected to happen when running the steps above -->

Users that are not created does not get their password changed.

##### ACTUAL RESULTS
<!--- Describe what actually happened. If possible run with extra verbosity (-vvvv) -->

<!--- Paste verbatim command output between quotes -->
```paste below
Password "hash" changed to '*'
```

generate_ssh_key=dict(type='bool'),
            ssh_key_bits=dict(type='int', default=ssh_defaults['bits']),
            ssh_key_type=dict(type='str', default=ssh_defaults['type']),
            ssh_key_file=dict(type='path'),
            ssh_key_comment=dict(type='str', default=ssh_defaults['comment']),
            ssh_key_passphrase=dict(type='str', no_log=True),
            update_password=dict(type='str', default='always', choices=['always', 'on_create']),
            expires=dict(type='float'),
            password_lock=dict(type='bool'),
            local=dict(type='bool'),
            profile=dict(type='str'),
            authorization=dict(type='str'),
            role=dict(type='str'),
        ),
        supports_check_mode=True,
        mutually_exclusive=[
            ('local', 'groups'),
            ('local', 'append')
        ]
    )
    user = User(module)
    user.check_password_encrypted()
    module.debug('User instantiated - platform %s' % user.platform)
    if user.distribution:
        module.debug('User instantiated - distribution %s' % user.distribution)
    rc = None
    out = ''
    err = ''
    result = {}
    result['name'] = user.name