##### SUMMARY
ansible_run_tags documentation says the default is empty ("[]") at https://docs.ansible.com/ansible/latest/reference_appendices/config.html#tags-run

However when running a debug print with no tags specified, we get this output:

```
- name: print tags
  debug:
    msg: "{{ ansible_run_tags }}"
```

```
$ ansible-playbook deploy.yml
```

```

TASK [workstation : print tags] ************************************************************************************************************************************************************************************************************************************************************
task path: /home/gdevenyi/projects/lozano_ansible/roles/workstation/tasks/main.yml:4
ok: [192.168.56.104] => {
    "msg": [
        "all"
    ]
}

```

<!--- HINT: Did you know the documentation has an "Edit on GitHub" link on every page ? -->

##### ISSUE TYPE
- Documentation Report

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

##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```paste below
2.9.9
```

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

```

##### OS / ENVIRONMENT
<!--- Provide all relevant information below, e.g. OS version, browser, etc. -->
Ubuntu 18.04
##### ADDITIONAL INFORMATION
<!--- Describe how this improves the documentation, e.g. before/after situation or screenshots -->

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

"""Process the command line args
        Subclasses need to implement this method.  This method validates and transforms the command
        line arguments.  It can be used to check whether conflicting values were given, whether filenames
        exist, etc.
        An implementation will look something like this::
            def post_process_args(self, options):
                options = super(MyCLI, self).post_process_args(options)
                if options.addition and options.subtraction:
                    raise AnsibleOptionsError('Only one of --addition and --subtraction can be specified')
                if isinstance(options.listofhosts, string_types):
                    options.listofhosts = string_types.split(',')
                return options
        """
        
        if hasattr(options, 'tags') and not options.tags:
            
            options.tags = ['all']
        if hasattr(options, 'tags') and options.tags:
            tags = set()
            for tag_set in options.tags:
                for tag in tag_set.split(u','):