Comment 28 for bug 1846789

I'm seeing this on master in CI too now:

https://zuul.opendev.org/t/openstack/build/78feeaaa93014e1ab7ef8b7fafa70eb7/log/primary/logs/kolla/keystone/keystone-apache-public-error.txt#14944

```
2020-06-24 15:21:10.668579 mod_wsgi (pid=34, process='keystone-public', application=''): Loading Python script file '/var/lib/kolla/venv/bin/keystone-wsgi-public'.
2020-06-24 15:21:10.669624 mod_wsgi (pid=34): Failed to exec Python script file '/var/lib/kolla/venv/bin/keystone-wsgi-public'.
2020-06-24 15:21:10.669662 mod_wsgi (pid=34): Exception occurred processing WSGI script '/var/lib/kolla/venv/bin/keystone-wsgi-public'.
2020-06-24 15:21:10.669837 Traceback (most recent call last):
2020-06-24 15:21:10.669879 File "/var/lib/kolla/venv/bin/keystone-wsgi-public", line 52, in <module>
2020-06-24 15:21:10.669882 application = initialize_public_application()
2020-06-24 15:21:10.669889 File "/var/lib/kolla/venv/lib/python3.6/site-packages/keystone/server/wsgi.py", line 24, in initialize_public_application
2020-06-24 15:21:10.669892 name='public', config_files=flask_core._get_config_files())
2020-06-24 15:21:10.669898 File "/var/lib/kolla/venv/lib/python3.6/site-packages/keystone/server/flask/core.py", line 157, in initialize_application
2020-06-24 15:21:10.669901 keystone.server.configure(config_files=config_files)
2020-06-24 15:21:10.670073 File "/var/lib/kolla/venv/lib/python3.6/site-packages/keystone/server/__init__.py", line 28, in configure
2020-06-24 15:21:10.670076 keystone.conf.configure()
2020-06-24 15:21:10.670081 File "/var/lib/kolla/venv/lib/python3.6/site-packages/keystone/conf/__init__.py", line 137, in configure
2020-06-24 15:21:10.670084 deprecated_since=versionutils.deprecated.STEIN))
2020-06-24 15:21:10.670089 File "/var/lib/kolla/venv/lib/python3.6/site-packages/oslo_config/cfg.py", line 2055, in __inner
2020-06-24 15:21:10.670092 result = f(self, *args, **kwargs)
2020-06-24 15:21:10.670098 File "/var/lib/kolla/venv/lib/python3.6/site-packages/oslo_config/cfg.py", line 2333, in register_cli_opt
2020-06-24 15:21:10.670100 raise ArgsAlreadyParsedError("cannot register CLI option")
2020-06-24 15:21:10.670115 oslo_config.cfg.ArgsAlreadyParsedError: arguments already parsed: cannot register CLI option
```