<!--- 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!
```

'''
        Runs the task with the loop items specified and collates the result
        into an array named 'results' which is inserted into the final result
        along with the item for which the loop ran.
        '''
        results = []
        
        
        
        task_vars = self._job_vars
        loop_var = 'item'
        index_var = None
        label = None
        loop_pause = 0
        extended = False
        templar = Templar(loader=self._loader, shared_loader_obj=self._shared_loader_obj, variables=self._job_vars)
        
        if self._task.loop_control:
            loop_var = templar.template(self._task.loop_control.loop_var)
            index_var = templar.template(self._task.loop_control.index_var)
            loop_pause = templar.template(self._task.loop_control.pause)
            extended = templar.template(self._task.loop_control.extended)
            
            label = self._task.loop_control.label
        
        if label is None:
            label = '{{' + loop_var + '}}'
        if loop_var in task_vars: