Comment 1 for bug 1898015

The 0 return code comes from here as I see:
https://opendev.org/openstack/oslo.config/src/commit/dce2afd7898d618336e1859283bcedea8336a7a2/oslo_config/cfg.py#L2960

raise SystemExit(2) or raise SystemExit('foo') should give what you expect.
I am not sure if it is intentionally not using argument for SystemExit.