Thanks Brian,
Actually I hit this problem initially with heat-cfntools which is not using upper-constraints in doc build
but has language=None explicitly set, so what you mentioned makes quite clear sense.
Quick grep shows a few instances of the hard-coded language=None . These should be commented out
before we get the constraint bumped.
openstack/python-swiftclient/releasenotes/source/conf.py:language = None
openstack/blazar/api-ref/source/conf.py:language = None
openstack/heat-agents/doc/source/conf.py:language = None
openstack/heat-agents/releasenotes/source/conf.py:language = None
openstack/swift/releasenotes/source/conf.py:language = None
openstack/storlets/releasenotes/source/conf.py:language = None
openstack/placement/releasenotes/source/conf.py:language = None
openstack/osc-lib/releasenotes/source/conf.py:language = None
openstack/python-heatclient/releasenotes/source/conf.py:language = None
openstack/trove-dashboard/releasenotes/source/conf.py:language = None
openstack/virtualbmc/releasenotes/source/conf.py:language = None
openstack/heat-templates/doc/source/conf.py:language = None
Disclaimer: The above list might be missing some projects.