<!--- Verify first that your issue is not already reported on GitHub -->
<!--- Also test if the latest release and devel branch are affected too -->
<!--- Complete *all* sections as described, this form is processed automatically -->

##### SUMMARY
`docker_login` reports no change even though it logged out.

##### ISSUE TYPE
- Bug Report

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

##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```paste below
ansible 2.8.1
  config file = /etc/ansible/ansible.cfg
  configured module search path = [u'/home/raphael/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/lib/python2.7/dist-packages/ansible
  executable location = /usr/bin/ansible
  python version = 2.7.15+ (default, Nov 27 2018, 23:36:35) [GCC 7.3.0]

```

##### 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. -->

Client: Ubuntu 18.04 LTS 4.18.0-24-generic, ansible 2.8.1
Server: RHE7 3.10.0-957.21.3.el7.x86_64


##### 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: Pull some Docker images 
  block:
  - name: Log into Harbor (Docker registry)
    docker_login:
        registry: "{{docker_registry}}"
        username: "{{harbor_user}}"
        password: "{{harbor_password}}"
        reauthorize: yes
  - name: Pull Docker images
    loop:
      - "some_image"
      - "other_image"
    docker_image:
      name: "{{ item }}"
      state: present
      source: pull
  always:
    - name: Docker logout
      docker_login:
        registry: "{{docker_registry}}"
        state: absent
```

##### EXPECTED RESULTS

Task `Docker logout` should report changes.


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

<!--- Paste verbatim command output between quotes -->
```paste below
TASK [gears : Log into Harbor (Docker registry)] 
<snip>
changed: [<snip>] => {
    "changed": true, 
    "invocation": {
        "module_args": {
            "api_version": "auto", 
            "ca_cert": null, 
            "client_cert": null, 
            "client_key": null, 
            "config_path": "/home/<snip>/.docker/config.json", 
            "debug": false, 
            "docker_host": "unix://var/run/docker.sock", 
            "email": null, 
            "password": "VALUE_SPECIFIED_IN_NO_LOG_PARAMETER", 
            "reauthorize": true, 
            "registry": "<snip>", 
            "registry_url": "<snip>, 
            "ssl_version": null, 
            "state": "present", 
            "timeout": 60, 
            "tls": false, 
            "tls_hostname": "localhost", 
            "username": "<snip>", 
            "validate_certs": false
        }
    }, 
    "login_result": {
        "IdentityToken": "", 
        "Status": "Login Succeeded"
    }
}

<snip>
TASK [gears : Pull Docker images]
ok:
<snip>

TASK [gears : Docker logout]
<snip>
ok: [<snip>] => {
    "changed": false, 
    "invocation": {
        "module_args": {
            "api_version": "auto", 
            "ca_cert": null, 
            "client_cert": null, 
            "client_key": null, 
            "config_path": "/home/<snip>/.docker/config.json", 
            "debug": false, 
            "docker_host": "unix://var/run/docker.sock", 
            "email": null, 
            "password": null, 
            "reauthorize": false, 
            "registry": "<snip>", 
            "registry_url": "<snip>", 
            "ssl_version": null, 
            "state": "absent", 
            "timeout": 60, 
            "tls": false, 
            "tls_hostname": "localhost", 
            "username": null, 
            "validate_certs": false
        }
    }, 
    "login_result": {}
}
```

But, on that host:

```
$ cat .docker/config.json | grep auth
	"auths": {}
```

When I remove the logout task, the login appears in that output. So logout _is_ effective. 
state:
    version_added: '2.3'
    description:
      - This controls the current state of the user. C(present) will login in a user, C(absent) will log them out.
      - To logout you only need the registry server, which defaults to DockerHub.
      - Before 2.1 you could ONLY log in.
      - Docker does not support 'logout' with a custom config file.
    type: str
    default: 'present'
    choices: ['present', 'absent']
extends_documentation_fragment:
  - docker
  - docker.docker_py_1_documentation
requirements:
  - "L(Docker SDK for Python,https://docker-py.readthedocs.io/en/stable/) >= 1.8.0 (use L(docker-py,https://pypi.org/project/docker-py/) for Python 2.6)"
  - "Docker API >= 1.20"
  - "Only to be able to logout, that is for I(state) = C(absent): the C(docker) command line utility"
author:
  - Olaf Kilian (@olsaki) <olaf.kilian@symanex.com>
  - Chris Houseknecht (@chouseknecht)
'''
EXAMPLES = '''
- name: Log into DockerHub
  docker_login:
    username: docker
    password: rekcod
- name: Log into private registry and force re-authorization
  docker_login:
    registry: your.private.registry.io
    username: yourself