https://github.com/ansible/ansible/blob/adcdee9bb0031577698246fcfc51f8af63a56a17/lib/ansible/playbook/task.py#L124

##### SUMMARY
Handlers can not be referenced with the `FQCN : handler name` notation if the handler name contains the role name.

Not sure what the reasoning is behind this, but a `httpd` role can't have a `restart httpd` handler name if you want to notify it with `notify: 'httpd : restart httpd'`

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
task handler fqcn

##### ANSIBLE VERSION
```
ansible 2.9.10
  config file = /home/twouters/.ansible.cfg
  configured module search path = ['/home/twouters/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/lib/python3.8/site-packages/ansible
  executable location = /usr/bin/ansible
  python version = 3.8.3 (default, May 17 2020, 18:15:42) [GCC 10.1.0]
```

##### CONFIGURATION
Default configuration

##### OS / ENVIRONMENT
All (N/A)

##### STEPS TO REPRODUCE
```
➜  issues-70582 $ find ./
./
./roles
./roles/test
./roles/test/handlers
./roles/test/handlers/main.yml
./roles/test/tasks
./roles/test/tasks/main.yml
./pb.yml
```

`pb.yml`
```yaml
---

- hosts: localhost
  roles:
    - test
```

`roles/test/tasks/main.yml`
```yaml
---

- name: always trigger handler
  command: /bin/true
  changed_when: True
  notify:
    - 'test : handler 1'

- name: always trigger handler 2
  command: /bin/true
  changed_when: True
  notify:
    - 'test : handler 2 test'
```

`roles/test/handlers/main.yml`
```yaml
---

- name: handler 1
  debug:
    msg: this is handler 1

- name: handler 2 test
  debug:
    msg: this handler is not found
```

##### EXPECTED RESULTS
Two handlers are detected.

##### ACTUAL RESULTS
Only the handler that doesn't contain the role name in its name gets detected

```
➜  issues-70582 $ ansible-playbook pb.yml           
[WARNING]: No inventory was parsed, only implicit localhost is available
[WARNING]: provided hosts list is empty, only localhost is available. Note that the implicit localhost does not
match 'all'

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

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

TASK [test : always trigger handler] ***************************************************************************
changed: [localhost]

TASK [test : always trigger handler 2] *************************************************************************
ERROR! The requested handler 'test : handler 2 test' was not found in either the main handlers list nor in the listening handlers list
```
self._tqm.send_callback('v2_runner_on_ok', task_result)
            
            if original_task.register:
                host_list = self.get_task_hosts(iterator, original_host, original_task)
                clean_copy = strip_internal_keys(module_response_deepcopy(task_result._result))
                if 'invocation' in clean_copy:
                    del clean_copy['invocation']
                for target_host in host_list:
                    self._variable_manager.set_nonpersistent_facts(target_host, {original_task.register: clean_copy})
            if do_handlers:
                self._pending_handler_results -= 1
            else:
                self._pending_results -= 1
            if original_host.name in self._blocked_hosts:
                del self._blocked_hosts[original_host.name]
            
            
            if original_task._role is not None and role_ran:  
                
                
                for (entry, role_obj) in iteritems(iterator._play.ROLE_CACHE[original_task._role.get_name()]):
                    if role_obj._uuid == original_task._role._uuid:
                        role_obj._had_task_run[original_host.name] = True
            ret_results.append(task_result)
            if one_pass or max_passes is not None and (cur_pass + 1) >= max_passes:
                break
            cur_pass += 1
        return ret_results
    def _wait_on_handler_results(self, iterator, handler, notified_hosts):