Test test_create_router_with_snat_explicit is failing on deletion of router. Error in neutron is like below:

2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource [req-65833112-d708-47f3-8227-3261cfda5af2 686c30b80c1f4583ae8a5e1c84141d0e 5d9cee455cbe479d8348db77f44c7553 - default default] delete failed: No details.: InvalidRequestError: Could not refresh instance '<Router
at 0x7fc3ea9bca10>'
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource Traceback (most recent call last):
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/neutron/api/v2/resource.py", line 98, in resource
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     result = method(request=request, **args)
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/neutron/api/v2/base.py", line 567, in delete
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     return self._delete(request, id, **kwargs)
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/neutron_lib/db/api.py", line 139, in wrapped
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     setattr(e, '_RETRY_EXCEEDED', True)
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/oslo_utils/excutils.py", line 220, in __exit__
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     self.force_reraise()
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/oslo_utils/excutils.py", line 196, in force_reraise
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     six.reraise(self.type_, self.value, self.tb)
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/neutron_lib/db/api.py", line 135, in wrapped
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     return f(*args, **kwargs)
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/oslo_db/api.py", line 154, in wrapper
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     ectxt.value = e.inner_exc
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/oslo_utils/excutils.py", line 220, in __exit__
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     self.force_reraise()
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/oslo_utils/excutils.py", line 196, in force_reraise
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     six.reraise(self.type_, self.value, self.tb)
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/oslo_db/api.py", line 142, in wrapper
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     return f(*args, **kwargs)
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/neutron_lib/db/api.py", line 183, in wrapped
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     LOG.debug("Retry wrapper got retriable exception: %s", e)
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/oslo_utils/excutils.py", line 220, in __exit__
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     self.force_reraise()
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/oslo_utils/excutils.py", line 196, in force_reraise
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     six.reraise(self.type_, self.value, self.tb)
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/neutron_lib/db/api.py", line 179, in wrapped
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     return f(*dup_args, **dup_kwargs)
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/neutron/api/v2/base.py", line 595, in _delete
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     obj_deleter(request.context, id, **kwargs)
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/networking_ovn/l3/l3_ovn.py", line 152, in delete_router
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     super(OVNL3RouterPlugin, self).delete_router(context, id)
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/neutron/db/l3_db.py", line 2005, in delete_router
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     super(L3_NAT_db_mixin, self).delete_router(context, id)
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/neutron_lib/db/api.py", line 233, in wrapped
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     return method(*args, **kwargs)
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/neutron_lib/db/api.py", line 139, in wrapped
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     setattr(e, '_RETRY_EXCEEDED', True)
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/oslo_utils/excutils.py", line 220, in __exit__
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     self.force_reraise()
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/oslo_utils/excutils.py", line 196, in force_reraise
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     six.reraise(self.type_, self.value, self.tb)
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/neutron_lib/db/api.py", line 135, in wrapped
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     return f(*args, **kwargs)
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/oslo_db/api.py", line 154, in wrapper
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     ectxt.value = e.inner_exc
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/oslo_utils/excutils.py", line 220, in __exit__
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     self.force_reraise()
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/oslo_utils/excutils.py", line 196, in force_reraise
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     six.reraise(self.type_, self.value, self.tb)
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/oslo_db/api.py", line 142, in wrapper
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     return f(*args, **kwargs)
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/neutron_lib/db/api.py", line 183, in wrapped
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     LOG.debug("Retry wrapper got retriable exception: %s", e)
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/oslo_utils/excutils.py", line 220, in __exit__
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     self.force_reraise()
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/oslo_utils/excutils.py", line 196, in force_reraise
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     six.reraise(self.type_, self.value, self.tb)
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/neutron_lib/db/api.py", line 179, in wrapped
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     return f(*dup_args, **dup_kwargs)
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/site-packages/neutron/db/l3_db.py", line 570, in delete_router
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     context.session.refresh(router)
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource   File "/usr/lib64/python2.7/site-packages/sqlalchemy/orm/session.py", line 1670, in refresh
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource     "Could not refresh instance '%s'" % instance_str(instance)
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource InvalidRequestError: Could not refresh instance '<Router at 0x7fc3ea9bca10>'
2019-12-02 08:03:41.019 28 ERROR neutron.api.v2.resource
2019-12-02 08:03:41.028 28 INFO neutron.wsgi [req-65833112-d708-47f3-8227-3261cfda5af2 686c30b80c1f4583ae8a5e1c84141d0e 5d9cee455cbe479d8348db77f44c7553 - default default] 172.17.0.212 "DELETE /v2.0/routers/999a82de-4b0d-4e5d-851c-bf07d84f452d HTTP/1.1" status: 500  len: 363 time: 33.0280960

But I'm not sure if that may be neutron or networking-ovn issue. But we don't see anything similar in neutron gate where ML2/ovs backend is used.