CALLBACK_VERSION et al are documented as required in
https://docs.ansible.com/ansible/2.10/dev_guide/developing_plugins.html#callback-plugins.
The need for document_fragment is noted in
cfa8075537/lib/ansible/plugins/callback/default.py (L28-L32)Fixes#758
This addresses the following error, seen while running
`ansible_tests.py`.
```
TASK [Gathering Facts gather_timeout=10, gather_subset=['all']]
****************
task path:
/home/alex/src/mitogen/tests/ansible/regression/issue_109__target_has_old_ansible_installed.yml:4
[WARNING]: Failure using method (v2_runner_on_start) in callback plugin
(<ansible.plugins.callback.nice_stdout.CallbackModule object at
0x7f76b3dad090>): 'show_per_host_start'
Callback Exception:
File
"/home/alex/src/mitogen/.tox/py27-ansible2.10/lib/python2.7/site-packages/ansible/executor/task_queue_manager.py",
line 372, in send_callback
method(*new_args, **kwargs)
File
"/home/alex/src/mitogen/.tox/py27-ansible2.10/lib/python2.7/site-packages/ansible/plugins/callback/default.py",
line 240, in v2_runner_on_start
if self.get_option('show_per_host_start'):
File
"/home/alex/src/mitogen/.tox/py27-ansible2.10/lib/python2.7/site-packages/ansible/plugins/callback/__init__.py",
line 91, in get_option
return self._plugin_options[k]
Callback Exception:
File
"/home/alex/src/mitogen/.tox/py27-ansible2.10/lib/python2.7/site-packages/ansible/executor/task_queue_manager.py",
line 372, in send_callback
method(*new_args, **kwargs)
File
"/home/alex/src/mitogen/.tox/py27-ansible2.10/lib/python2.7/site-packages/ansible/plugins/callback/default.py",
line 240, in v2_runner_on_start
if self.get_option('show_per_host_start'):
File
"/home/alex/src/mitogen/.tox/py27-ansible2.10/lib/python2.7/site-packages/ansible/plugins/callback/__init__.py",
line 91, in get_option
return self._plugin_options[k]
[task 339882] 00:00:08.172036 D ansible_mitogen.affinity: CPU mask for
WorkerProcess: 0x000004
Callback Exception:
File
"/home/alex/src/mitogen/.tox/py27-ansible2.10/lib/python2.7/site-packages/ansible/executor/task_queue_manager.py",
line 372, in send_callback
method(*new_args, **kwargs)
File
"/home/alex/src/mitogen/.tox/py27-ansible2.10/lib/python2.7/site-packages/ansible/plugins/callback/default.py",
line 240, in v2_runner_on_start
if self.get_option('show_per_host_start'):
File
"/home/alex/src/mitogen/.tox/py27-ansible2.10/lib/python2.7/site-packages/ansible/plugins/callback/__init__.py",
line 91, in get_option
return self._plugin_options[k]
```
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