##### SUMMARY
add_host will return 'changed' for every invocation, it does not matter if the host already existed and no changes were actually made to inventory

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
<!--- Write the short name of the module, plugin, task or feature below, use your best guess if unsure -->
add_host
##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```paste below
2.7, 2.8, 2.9, 2.10
```

##### 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. -->
all

##### STEPS TO REPRODUCE

Simplest example, but also happens when specifying variables and/or groups

test.yml
```yaml
- hosts: localhost
  gather_facts: false
  tasks:
    - add_host: name=testhost
```
test_inv.ini
```ini
testhost
```
run:
``` ansible-playbook -i test_inv.ini test.yml```

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

##### EXPECTED RESULTS
<!--- Describe what you expected to happen when running the steps above -->
```
 _________________
< TASK [add_host] >
 -----------------
       \   ,__,
        \  (oo)____
           (__)    )\
              ||--|| *

OK: [localhost]
```

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

<!--- Paste verbatim command output between quotes -->
```paste below
 _________________
< TASK [add_host] >
 -----------------
       \   ,__,
        \  (oo)____
           (__)    )\
              ||--|| *

changed: [localhost]
```

"""Closure to wrap ``StrategyBase._process_pending_results`` and invoke the task debugger"""
    @functools.wraps(func)
    def inner(self, iterator, one_pass=False, max_passes=None, do_handlers=False):
        status_to_stats_map = (
            ('is_failed', 'failures'),
            ('is_unreachable', 'dark'),
            ('is_changed', 'changed'),
            ('is_skipped', 'skipped'),
        )
        
        prev_host_states = iterator._host_states.copy()
        results = func(self, iterator, one_pass=one_pass, max_passes=max_passes, do_handlers=do_handlers)
        _processed_results = []
        for result in results:
            task = result._task
            host = result._host
            _queued_task_args = self._queued_task_cache.pop((host.name, task._uuid), None)
            task_vars = _queued_task_args['task_vars']
            play_context = _queued_task_args['play_context']
            
            try:
                prev_host_state = prev_host_states[host.name]
            except KeyError:
                prev_host_state = iterator.get_host_state(host)
            while result.needs_debugger(globally_enabled=self.debugger_active):
                next_action = NextAction()
                dbg = Debugger(task, host, task_vars, play_context, result, next_action)
                dbg.cmdloop()
                if next_action.result == NextAction.REDO: