Comment 2 for bug 1886807

My previous comment is wrong. It looks like race-condition. Full log:
http://paste.openstack.org/show/796117/

There are many errors linked to failed tests. All of those fails on similar issue:

Jul 18 00:33:03.396324 ubuntu-bionic-rax-iad-0018417357 neutron-server[7625]: ERROR neutron.services.ovn_l3.plugin [None req-74120644-67fe-4b11-964e-86299ee5407f tempest-RoutersIpV6Test-2067377291 tempest-RoutersIpV6Test-2067377291] Unable to update lrouter for deb1a165-eaaa-4406-aee5-bacc5d106260: sqlalchemy.orm.exc.StaleDataError: UPDATE statement on table 'standardattributes' expected to update 1 row(s); 0 were matched.
Jul 18 00:33:03.396324 ubuntu-bionic-rax-iad-0018417357 neutron-server[7625]: ERROR neutron.services.ovn_l3.plugin Traceback (most recent call last):
Jul 18 00:33:03.396324 ubuntu-bionic-rax-iad-0018417357 neutron-server[7625]: ERROR neutron.services.ovn_l3.plugin File "/opt/stack/neutron/neutron/services/ovn_l3/plugin.py", line 157, in update_router
Jul 18 00:33:03.396324 ubuntu-bionic-rax-iad-0018417357 neutron-server[7625]: ERROR neutron.services.ovn_l3.plugin original_router)
...
Jul 18 00:33:03.396324 ubuntu-bionic-rax-iad-0018417357 neutron-server[7625]: ERROR neutron.services.ovn_l3.plugin File "/usr/local/lib/python3.6/dist-packages/sqlalchemy/orm/persistence.py", line 1028, in _emit_update_statements
Jul 18 00:33:03.396324 ubuntu-bionic-rax-iad-0018417357 neutron-server[7625]: ERROR neutron.services.ovn_l3.plugin % (table.description, len(records), rows)
Jul 18 00:33:03.396324 ubuntu-bionic-rax-iad-0018417357 neutron-server[7625]: ERROR neutron.services.ovn_l3.plugin sqlalchemy.orm.exc.StaleDataError: UPDATE statement on table 'standardattributes' expected to update 1 row(s); 0 were matched.

Looks like main cause is somewhere around this function:

Jul 18 01:09:50.692083 ubuntu-bionic-rax-iad-0018417357 neutron-server[7625]: ERROR oslo_db.api File "/opt/stack/neutron/neutron/services/ovn_l3/plugin.py", line 163, in update_router