<!--- 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
<!--- Explain the problem briefly below -->
When looping `include_tasks`, the loop control `loop_var` property is not defined in the included task, when the `loop_var` property has been assigned with a template.

##### ISSUE TYPE
- Bug Report

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

##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```paste below
ansible 2.8.1
  config file = /playbooks/ansible.cfg
  configured module search path = ['/root/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/local/lib/python3.7/site-packages/ansible
  executable location = /usr/local/bin/ansible
  python version = 3.7.3 (default, Jun 11 2019, 01:05:09) [GCC 6.3.0 20170516]
```

##### OS / ENVIRONMENT
<!--- Provide all relevant information below, e.g. target OS versions, network device firmware, etc. -->
Redhat7
Archlinux


##### STEPS TO REPRODUCE
<!--- Describe exactly how to reproduce the problem, using a minimal test-case -->

<!--- Paste example playbooks or commands between quotes below -->
```yaml
---
# main.yml
- hosts: localhost
  vars:
    loop_var_name: custom_var

  tasks:
    - include_tasks: looped-include.yml
      loop:
        - first
        - second
      loop_control:
        loop_var: "{{ loop_var_name }}"
```

```yaml
---
# looped-include.yml
- name: Print looped var
  debug:
    var: custom_var

- name: Loop default item var
  debug:
    var: item
```

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

##### EXPECTED RESULTS
<!--- Describe what you expected to happen when running the steps above -->
We expect the variabe `custom_var` to be the looped variable, and `item` to be undefined. 

##### ACTUAL RESULTS
<!--- Describe what actually happened. If possible run with extra verbosity (-vvvv) -->
Neither `custom_var` nor `item` are defined in the looped included task.

<!--- Paste verbatim command output between quotes -->
```paste below
PLAY [localhost] *****************************************************************************************

TASK [Gathering Facts] ***********************************************************************************
ok: [localhost]
included: /ansible-bug/looped-include.yml for localhost
included: /ansible-bug/looped-include.yml for localhost

TASK [Print looped var] **********************************************************************************
ok: [localhost] => 
  custom_var: VARIABLE IS NOT DEFINED!

TASK [Loop default item var] *****************************************************************************
ok: [localhost] => 
  item: VARIABLE IS NOT DEFINED!

TASK [Print looped var] **********************************************************************************
ok: [localhost] => 
  custom_var: VARIABLE IS NOT DEFINED!

TASK [Loop default item var] *****************************************************************************
ok: [localhost] => 
  item: VARIABLE IS NOT DEFINED!
```

'''
        The main executor entrypoint, where we determine if the specified
        task requires looping and either runs the task with self._run_loop()
        or self._execute(). After that, the returned results are parsed and
        returned as a dict.
        '''
        display.debug("in run() - task %s" % self._task._uuid)
        try:
            try:
                items = self._get_loop_items()
            except AnsibleUndefinedVariable as e:
                
                items = None
                self._loop_eval_error = e
            if items is not None:
                if len(items) > 0:
                    item_results = self._run_loop(items)
                    
                    res = dict(results=item_results)
                    
                    for item in item_results:
                        if 'changed' in item and item['changed'] and not res.get('changed'):