support pyroute2 0.5.13

[sean mooney]

pytroute2 version 0.5.13 changed the behaviour of ip.link_lookup
such that if the device is not found it now returns an empty list instead
of raising ipexc.NetlinkError.

as we have unit test that assert the old behaviour this breaks the os-vif unit tests.
recently https://review.opendev.org/#/c/743277/ was merged to bump the pytroute2 version
but the requirements repo does not currently run the os-vif unit test so this breakage was not seen.

https://review.opendev.org/#/c/744803/1 adds a new cross job to track that but os-vif should also be updated to account for the new behaviour.

[Rodolfo Alonso (rodolfo-alonso-hernandez)]

This error is also affecting Neutron: https://github.com/openstack/neutron/blob/5999716cfc4a00ac426e016eabbb51247ba0b190/neutron/privileged/agent/linux/ip_lib.py#L244

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/744956

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/744809
Committed: https://git.openstack.org/cgit/openstack/os-vif/commit/?id=c8703df185ae3a3445e1e3368ee3229f485b85d9
Submitter: Zuul
Branch: master

commit c8703df185ae3a3445e1e3368ee3229f485b85d9
Author: Sean Mooney <email address hidden>
Date: Wed Aug 5 00:07:11 2020 +0000

    support pyroute2 0.5.13

    This change modifes os-vif add interface to account
    for the new behavior of link_lookup.
    In 0.5.13 if a link is not found link_lookup returns an
    empty list. In previous releases it raised ipexc.NetlinkError.

    Closes-bug: #1890353

    Change-Id: I567afb544425c1b91d98968a0b597be718869089

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/744956
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=e5ce19318921c44f2f5ed4568b31b04d82a17fd4
Submitter: Zuul
Branch: master

commit e5ce19318921c44f2f5ed4568b31b04d82a17fd4
Author: Rodolfo Alonso Hernandez <email address hidden>
Date: Wed Aug 5 17:36:01 2020 +0000

    Support pyroute2 0.5.13

    Since [1], pyroute2 0.5.13 is supported.

    In this new version, "link_lookup" do not raise a NetlinkError
    exception if the device does not exist; instead returns an empty
    list.

    This patch handles both implementations.

    [1]https://review.opendev.org/#/c/743277/

    Change-Id: I77ef374ecb776966ea13499755777e2d763d884b
    Closes-Bug: #1890353