[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/17f931b9ef2545dfb58ca78c756689... - openstack-tox-docs https://zuul.opendev.org/t/openstack/build/5a4e3a2422184876812602481c56328b : SUCCESS in 6m 33s - openstack-tox-py27 https://zuul.opendev.org/t/openstack/build/7c6f8aaa26e64ef297b6f843eb0d6af6 : SUCCESS in 3m 00s - openstack-tox-py36 https://zuul.opendev.org/t/openstack/build/6957a266150341799cf03e8daff7277e : SUCCESS in 3m 58s - openstack-tox-py37 https://zuul.opendev.org/t/openstack/build/17e77cd52f7f4222aa173d6793ffa7d1 : FAILURE in 3m 57s