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Hi,

Some time ago we backported in Neutron patch [1] which caused bug [2].
Patch [1] was merged in the Ussuri development cycle so it is already in 
Ussuri and Victoria. Our mistake was that we merged it then without bump of 
the RPC version and without code which would provide backward compatybility 
between old agent and new neutron-server and that's why [2] happens.

Now, as we know that, we have proposed patch [3] to fix it in master branch.
And my question is - can we backport fix [3] to the stable/victoria and stable/
ussuri to fix the original issue caused by [1] there? 
In general I know that we shouldn't do that but here are the reasons why we 
would like to do it in this specific case:
- rpc version which we want to change now wasn't changed since Train at least 
so there will be no any conflict with that,
- bump rpc version now and provide backward compatybility on neutron-server 
will make upgrades Train->Ussuri and minor updates in Ussuri easier as there 
will be no similar issue like is described in [2] anymore,
- patch [1] was already included in Ussuri and Victoria from master branch, it 
wasn't really cherry-picked there so it actually should be there since the 
beginning.

Based on those reasons mentioned about and also becuase in general it is 
forbiden by stable policy to backport changes like that to stable branches I 
would like to know opinion from wider community, especially stable-core-maint 
team, about what would be the best approach to fix that issue: backport of [3] 
to stable/{ussuri,victoria} or revert [1] in stable/{ussuri,victoria}.

[1] https://review.opendev.org/c/openstack/neutron/+/712632
[2] https://bugs.launchpad.net/neutron/+bug/1903531
[3] https://review.opendev.org/c/openstack/neutron/+/764108

-- 
Slawek Kaplonski
Principal Software Engineer
Red Hat