Ussuri-only: Network segments are not tried out for allocation

[Thiago Paiva Brito]

* High level description: When we get a list of segments to choose from, and the first segment is already allocated, it fails right away returning RetryRequest exception, the the other segments are never tried out.

I explain it a little further on the comments of PatchSet 1 here: https://review.opendev.org/c/openstack/neutron/+/803986/1

This actually works at master due to a side effect of a refactoring that was done on https://opendev.org/openstack/neutron/commit/6eaa6d83d7c7f07fd4bf04879c91582de504eff4 to randomize the selection of segments, but on stable/ussuri, when not specifying the provider_network_type, we got into a situation where we had segments to allocate in vlan but neutron was allocating vxlan instead.

* Pre-conditions: network_segment_range plugin enabled and several vlan project networks created on the system

* Step-by-step reproduction steps: openstack --os-username 'project1_admin' --os-password '******' --os-project-name project1 --os-auth-url http://keystone.openstack.svc.cluster.local/v3 --os-user-domain-name Default --os-project-domain-name Default --os-identity-api-version 3 --os-interface internal --os-region-name RegionOne network create network11

* Expected output: network created successfully (there was available ranges)

* Actual output: HttpException: 503, Unable to create the network. No tenant network is available for allocation.

* Version:
  ** OpenStack version: stable/ussuri
  ** Linux distro: Centos 7
  ** Deployment: StarlingX Openstack

* Perceived severity: Major - System is usable in some circumstances

[Slawek Kaplonski (slaweq)]

You said it is fixed in master by https://review.opendev.org/c/openstack/neutron/+/783639 but that patch is only in stable/Wallaby and master. So I think that the same issue is also in Victoria, right?

[Slawek Kaplonski (slaweq)]

This bug has had a related patch abandoned and has been automatically un-assigned due to inactivity. Please re-assign yourself if you are continuing work or adjust the state as appropriate if it is no longer valid.

[OpenStack Infra (hudson-openstack)]

Change abandoned by "Slawek Kaplonski <email address hidden>" on branch: stable/ussuri
Review: https://review.opendev.org/c/openstack/neutron/+/803986
Reason: This review is > 4 weeks without comment, and failed Zuul jobs the last time it was checked. We are abandoning this for now. Feel free to reactivate the review by pressing the restore button and leaving a 'recheck' comment to get fresh test results.

[Thiago Paiva Brito (outbrito)]

In fact, the patches that fix that problem (although as a side effect) were already cherry-picked and merged on the stable branches:

train: https://review.opendev.org/c/openstack/neutron/+/808160
ussuri: https://review.opendev.org/c/openstack/neutron/+/804999
victoria: https://review.opendev.org/c/openstack/neutron/+/805000
wallaby: https://review.opendev.org/c/openstack/neutron/+/783639

Thanks Slawek and Rodolfo for those.