[Openstack-stable-maint] Stable check of openstack/oslo.serialization for ref refs/heads/stable/train failed

Build failed. https://zuul.opendev.org/t/openstack/buildset/5ba81d3b30fe4207a34585dae7fa99... - openstack-tox-docs https://zuul.opendev.org/t/openstack/build/bd841ce291f948e195b16720805c1161 : SUCCESS in 3m 18s - openstack-tox-py27 https://zuul.opendev.org/t/openstack/build/730f9bcf47a14ae2962bd8c93e8aab1c : SUCCESS in 3m 38s - openstack-tox-py36 https://zuul.opendev.org/t/openstack/build/f47734a894264d8c86a38820fb286f68 : SUCCESS in 3m 25s - openstack-tox-py37 https://zuul.opendev.org/t/openstack/build/046dbea5ad034e6c813e8e89f03190b9 : FAILURE in 4m 27s