[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/a9200f94f6304b38b72ef5c635c5dc... - openstack-tox-docs https://zuul.opendev.org/t/openstack/build/da5fda7884f94bc4b5d6de1221833128 : SUCCESS in 3m 16s - openstack-tox-py27 https://zuul.opendev.org/t/openstack/build/7a3ed98c262e4a3aacbe923b362aa61f : SUCCESS in 5m 34s - openstack-tox-py36 https://zuul.opendev.org/t/openstack/build/0b7c9cde7a884cf88dafd8ad376064ca : SUCCESS in 3m 49s - openstack-tox-py37 https://zuul.opendev.org/t/openstack/build/bf846177068f42f49b9c824473c68482 : FAILURE in 4m 39s