Comment 4 for bug 1881995

It is reproduced on my multinode devstack with stable/queens with one router, no VMs or other ports. Logs with reproduction of issue http://paste.openstack.org/show/794506/
As you can see no rules with ip_forward applied.
Some debug logs with issue http://paste.openstack.org/show/794507/ - in this logs you can see that snat namespace does not exits when _create_dvr_gateway started and was created later, but was not properly initialized.

The odd thing about reproduction that I see other behavior of L3 agent (dvr_snat) as well on rescheduling router http://paste.openstack.org/show/794508/ - in this case snat namespace got initialized at the very beginning properly. But with several number of reschedule attempts I hit the issue anyway.