Neutron's unit tests are failing with ovsdbapp from master branch

Example of periodic job failure (from 20.05.2020): https://2dcdf6f228f178cd0f37-585b06f1274d5f0e5ed27601745f1d4b.ssl.cf5.rackcdn.com/periodic/opendev.org/openstack/neutron/master/openstack-tox-py36-with-ovsdbapp-master/e942877/testr_results.html

Example of failed test:

2020-05-20 06:41:03.878276 | ubuntu-bionic | neutron.tests.unit.plugins.ml2.drivers.ovn.mech_driver.ovsdb.test_impl_idl_ovn.TestNBImplIdlOvn.test_get_address_sets
2020-05-20 06:41:03.878295 | ubuntu-bionic | ---------------------------------------------------------------------------------------------------------------------
2020-05-20 06:41:03.878313 | ubuntu-bionic |
2020-05-20 06:41:03.878331 | ubuntu-bionic | Captured traceback:
2020-05-20 06:41:03.878349 | ubuntu-bionic | ~~~~~~~~~~~~~~~~~~~
2020-05-20 06:41:03.878368 | ubuntu-bionic | Traceback (most recent call last):
2020-05-20 06:41:03.878386 | ubuntu-bionic |
2020-05-20 06:41:03.878417 | ubuntu-bionic | File "/home/zuul/src/opendev.org/openstack/neutron/neutron/tests/unit/plugins/ml2/drivers/ovn/mech_driver/ovsdb/test_impl_idl_ovn.py", line 343, in setUp
2020-05-20 06:41:03.878437 | ubuntu-bionic | self.nb_ovn_idl = impl_idl_ovn.OvsdbNbOvnIdl(mock.Mock())
2020-05-20 06:41:03.878456 | ubuntu-bionic |
2020-05-20 06:41:03.878474 | ubuntu-bionic | File "/home/zuul/src/opendev.org/openstack/neutron/neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/impl_idl_ovn.py", line 162, in __init__
2020-05-20 06:41:03.878493 | ubuntu-bionic | super(OvsdbNbOvnIdl, self).__init__(connection)
2020-05-20 06:41:03.878511 | ubuntu-bionic |
2020-05-20 06:41:03.878530 | ubuntu-bionic | File "/home/zuul/src/opendev.org/openstack/neutron/neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/impl_idl_ovn.py", line 63, in __init__
2020-05-20 06:41:03.878548 | ubuntu-bionic | super(Backend, self).__init__(connection)
2020-05-20 06:41:03.878567 | ubuntu-bionic |
2020-05-20 06:41:03.878585 | ubuntu-bionic | File "/home/zuul/src/opendev.org/openstack/neutron/.tox/py36/lib/python3.6/site-packages/ovsdbapp/backend/ovs_idl/__init__.py", line 33, in __init__
2020-05-20 06:41:03.878603 | ubuntu-bionic | self.autocreate_indices()
2020-05-20 06:41:03.878622 | ubuntu-bionic |
2020-05-20 06:41:03.878640 | ubuntu-bionic | File "/home/zuul/src/opendev.org/openstack/neutron/.tox/py36/lib/python3.6/site-packages/ovsdbapp/backend/ovs_idl/__init__.py", line 67, in autocreate_indices
2020-05-20 06:41:03.878659 | ubuntu-bionic | tables = set(self.idl.tables.keys())
2020-05-20 06:41:03.878677 | ubuntu-bionic |
2020-05-20 06:41:03.878695 | ubuntu-bionic | TypeError: 'Mock' object is not iterable

There is 21 tests failing like that and the error seems similar in all cases.