##### 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 '*'
```

test1:
                password = *
                lastupdate = 1553695126
        """
        b_name = to_bytes(self.name)
        b_passwd = b''
        b_expires = b''
        if os.path.exists(self.SHADOWFILE) and os.access(self.SHADOWFILE, os.R_OK):
            with open(self.SHADOWFILE, 'rb') as bf:
                b_lines = bf.readlines()
            b_passwd_line = b''
            b_expires_line = b''
            try:
                for index, b_line in enumerate(b_lines):
                    
                    if b_line.startswith(b'%s:' % b_name):
                        b_passwd_line = b_lines[index + 1]
                        b_expires_line = b_lines[index + 2]
                        break
                
                if b' = ' in b_passwd_line:
                    b_passwd = b_passwd_line.split(b' = ', 1)[-1].strip()
                if b' = ' in b_expires_line:
                    b_expires = b_expires_line.split(b' = ', 1)[-1].strip()
            except IndexError:
                self.module.fail_json(msg='Failed to parse shadow file %s' % self.SHADOWFILE)
        passwd = to_native(b_passwd)
        expires = to_native(b_expires) or -1
        return passwd, expires
class HPUX(User):