/usr/bin/neutron-db-manage", db-sync fails w/ unexpected keyword argument 'sync_backref'

Traceback (most recent call last):
  File "/usr/bin/neutron-db-manage", line 10, in <module>
    sys.exit(main())
  File "/usr/lib/python3.6/site-packages/neutron/db/migration/cli.py", line 660, in main
    return_val |= bool(CONF.command.func(config, CONF.command.name))
  File "/usr/lib/python3.6/site-packages/neutron/db/migration/cli.py", line 182, in do_upgrade
    run_sanity_checks(config, revision)
  File "/usr/lib/python3.6/site-packages/neutron/db/migration/cli.py", line 644, in run_sanity_checks
    script_dir.run_env()
  File "/usr/lib/python3.6/site-packages/alembic/script/base.py", line 489, in run_env
    util.load_python_file(self.dir, "env.py")
  File "/usr/lib/python3.6/site-packages/alembic/util/pyfiles.py", line 98, in load_python_file
    module = load_module_py(module_id, path)
  File "/usr/lib/python3.6/site-packages/alembic/util/compat.py", line 184, in load_module_py
    spec.loader.exec_module(module)
  File "<frozen importlib._bootstrap_external>", line 678, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/usr/lib/python3.6/site-packages/neutron/db/migration/alembic_migrations/env.py", line 24, in <module>
    from neutron.db.migration.models import head # noqa
  File "/usr/lib/python3.6/site-packages/neutron/db/migration/models/head.py", line 29, in <module>
    from neutron.db import agentschedulers_db # noqa
  File "/usr/lib/python3.6/site-packages/neutron/db/agentschedulers_db.py", line 42, in <module>
    from neutron.objects import network
  File "/usr/lib/python3.6/site-packages/neutron/objects/network.py", line 33, in <module>
    from neutron.objects.qos import binding
  File "/usr/lib/python3.6/site-packages/neutron/objects/qos/binding.py", line 23, in <module>
    from neutron.db.qos import models as qos_db_model
  File "/usr/lib/python3.6/site-packages/neutron/db/qos/models.py", line 39, in <module>
    class QosNetworkPolicyBinding(model_base.BASEV2):
  File "/usr/lib/python3.6/site-packages/neutron/db/qos/models.py", line 63, in QosNetworkPolicyBinding
    sync_backref=False)
TypeError: relationship() got an unexpected keyword argument 'sync_backref'

https://logserver.rdoproject.org/openstack-component-network/opendev.org/openstack/tripleo-ci/master/periodic-tripleo-ci-centos-8-multinode-1ctlr-featureset010-network-master/3658519/logs/undercloud/var/log/extra/podman/containers/neutron_db_sync/stdout.log.txt.gz

https://logserver.rdoproject.org/openstack-component-network/opendev.org/openstack/tripleo-ci/master/periodic-tripleo-ci-centos-8-standalone-network-master/7988ca2/logs/undercloud/var/log/extra/podman/containers/neutron_db_sync/stdout.log.txt.gz