##### SUMMARY
Setting `extended: yes` in `loop_control` doesn't provide `ansible_loop` inside the loop.

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
loop_control

##### ANSIBLE VERSION
```
ansible 2.9.0.dev0
  config file = None
  configured module search path = ['/home/kustodian/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /home/kustodian/git/github/ansible/lib/ansible
  executable location = /home/kustodian/git/github/ansible/bin/ansible
  python version = 3.7.4 (default, Jul 16 2019, 07:12:58) [GCC 9.1.0]
```
This also doesn't work on 2.8.4

##### CONFIGURATION
```
```

##### OS / ENVIRONMENT
ArchLinux

##### STEPS TO REPRODUCE
Create two files:
```yaml
# play.yml
---
- hosts: localhost
  connection: local
  tasks:
    - include_tasks: inner.yml
      loop:
        - 1
        - 2
        - 3
      loop_control:
        extended: yes
```
```
# inner.yml
- debug:
    var: ansible_loop
```
and run:
```
ansible-playbook play.yml -i localhost,
```

##### EXPECTED RESULTS
Ansible should print the value of `ansible_loop` three times.

##### ACTUAL RESULTS
It actually prints that `ansible_loop` is undefined:
```
$ ansible-playbook play.yml -i localhost,

PLAY [localhost] *******************************************************************************************************************************************************************************************

TASK [Gathering Facts] *************************************************************************************************************************************************************************************
ok: [localhost]

TASK [include_tasks] ***************************************************************************************************************************************************************************************
included: /tmp/inner.yml for localhost
included: /tmp/inner.yml for localhost
included: /tmp/inner.yml for localhost

TASK [debug] ***********************************************************************************************************************************************************************************************
ok: [localhost] => {
    "ansible_loop": "VARIABLE IS NOT DEFINED!"
}

TASK [debug] ***********************************************************************************************************************************************************************************************
ok: [localhost] => {
    "ansible_loop": "VARIABLE IS NOT DEFINED!"
}

TASK [debug] ***********************************************************************************************************************************************************************************************
ok: [localhost] => {
    "ansible_loop": "VARIABLE IS NOT DEFINED!"
}

PLAY RECAP *************************************************************************************************************************************************************************************************
localhost                  : ok=7    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0
```

def __init__(self, filename, args, vars, task, is_role=False):
        self._filename = filename
        self._args = args
        self._vars = vars
        self._task = task
        self._hosts = []
        self._is_role = is_role
    def add_host(self, host):
        if host not in self._hosts:
            self._hosts.append(host)
            return
        raise ValueError()
    def __eq__(self, other):
        return (other._filename == self._filename and
                other._args == self._args and
                other._vars == self._vars and
                other._task._parent._uuid == self._task._parent._uuid)
    def __repr__(self):
        return "%s (args=%s vars=%s): %s" % (self._filename, self._args, self._vars, self._hosts)
    @staticmethod
    def process_include_results(results, iterator, loader, variable_manager):
        included_files = []
        task_vars_cache = {}
        for res in results:
            original_host = res._host
            original_task = res._task
            if original_task.action in ('include', 'include_tasks', 'include_role'):
                if original_task.loop:
                    if 'results' not in res._result:
                        continue