Comment 4 for bug 1911920

Happening again:
https://review.opendev.org/c/openstack/charm-keystone-saml-mellon/+/761564
https://openstack-ci-reports.ubuntu.com/artifacts/test_charm_pipeline_func_full/openstack/charm-keystone-saml-mellon/761564/3/7824/index.html

We're getting a CERTIFICATE_VERIFY_FAILED in zaza/openstack/charm_tests/vault/setup.py:validate_ca(cacertificate, application=validation_application) with validation_application being keystone.

It seems indeed like the latest cert-related fixes may haven't made their way into the latest keystone charm yet as this review hasn't landed yet:
https://review.opendev.org/c/openstack/charm-keystone/+/771022