[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/50976ca490f04b598dfd62c1be6136... - openstack-tox-docs https://zuul.opendev.org/t/openstack/build/566ca88467f64a5998fb0e8e4b63137c : SUCCESS in 3m 53s - openstack-tox-py27 https://zuul.opendev.org/t/openstack/build/724bd58905734f189b34e53cd5672241 : FAILURE in 2m 02s - openstack-tox-py36 https://zuul.opendev.org/t/openstack/build/91829497aadc4cdf9486ba33c4eea57a : SUCCESS in 3m 16s - openstack-tox-py37 https://zuul.opendev.org/t/openstack/build/00a6ac5dab5e481ea7a0d57ea90aa680 : SUCCESS in 3m 04s