##### SUMMARY
helpers contains call to Display.deprecated or AnsibleModule.deprecate and is scheduled for removal

```
lib/ansible/playbook/helpers.py:158:20: ansible-deprecated-version: Deprecated version ('2.12') found in call to Display.deprecated or AnsibleModule.deprecate (0%)
lib/ansible/playbook/helpers.py:255:24: ansible-deprecated-version: Deprecated version ('2.12') found in call to Display.deprecated or AnsibleModule.deprecate (0%)
lib/ansible/playbook/helpers.py:298:24: ansible-deprecated-version: Deprecated version ('2.12') found in call to Display.deprecated or AnsibleModule.deprecate (0%)
lib/ansible/playbook/helpers.py:336:20: ansible-deprecated-version: Deprecated version ('2.12') found in call to Display.deprecated or AnsibleModule.deprecate (0%)
```

##### ISSUE TYPE
 - Bug Report

##### COMPONENT NAME
```
lib/ansible/playbook/helpers.py
```

##### ANSIBLE VERSION
```
2.12
```

##### CONFIGURATION
N/A

##### OS / ENVIRONMENT
N/A

##### STEPS TO REPRODUCE
N/A

##### EXPECTED RESULTS
N/A

##### ACTUAL RESULTS
N/A

ds = [{'block': None}]
        self.assertRaisesRegexp(errors.AnsibleParserError,
                                "A malformed block was encountered",
                                helpers.load_list_of_tasks,
                                ds, play=self.mock_play,
                                variable_manager=self.mock_variable_manager, loader=self.fake_loader)
    def test_unknown_action(self):
        action_name = 'foo_test_unknown_action'
        ds = [{'action': action_name}]
        res = helpers.load_list_of_tasks(ds, play=self.mock_play,
                                         variable_manager=self.mock_variable_manager, loader=self.fake_loader)
        self._assert_is_task_list_or_blocks(res)
        self.assertEqual(res[0].action, action_name)
    def test_block_unknown_action(self):
        action_name = 'foo_test_block_unknown_action'
        ds = [{
            'block': [{'action': action_name}]
        }]
        res = helpers.load_list_of_tasks(ds, play=self.mock_play,
                                         variable_manager=self.mock_variable_manager, loader=self.fake_loader)
        self._assert_is_task_list_or_blocks(res)
        self.assertIsInstance(res[0], Block)
        self._assert_default_block(res[0])
    def _assert_default_block(self, block):