wait_until_true is not rootwrap daemon friendly

[Jakub Libosvar]

As wait_until_true uses an eventlet timeout, it can happen that timeout exception is raised while waiting for output from rootwrap daemon. This leaves data in rwd socket and next attempt to run command via rootwrap daemon returns the previous data. There is a bug reported on oslo.rootwrap - https://bugs.launchpad.net/neutron/+bug/1654287

With a switch of fullstack tests to use rootwrap, it happens a lot that timeouts are raised while running commands in rwd (eg. http://logs.openstack.org/67/488567/2/check/gate-neutron-dsvm-fullstack-ubuntu-xenial/eb8f9a3/testr_results.html.gz)

This bug is to track down an eventlet free solution - we can generalize approach here https://review.openstack.org/#/c/421325/3/neutron/cmd/netns_cleanup.py and since we'll get rid of eventlet dependency, we can move wait_until_true to neutron-lib.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/510161

[OpenStack Infra (hudson-openstack)]

Change abandoned by Jakub Libosvar (<email address hidden>) on branch: master
Review: https://review.openstack.org/510161
Reason: Abandoning in favor of https://review.openstack.org/#/c/514547/

[Jakub Libosvar (libosvar)]

Bug https://bugs.launchpad.net/neutron/+bug/1654287 was fixed and released. We'll be monitoring this one but closing for now.

[Ihar Hrachyshka (ihar-hrachyshka)]

I suggest we close the bug since oslo.rootwrap fixes landed and we haven't seen the failure since then. We can reopen it later if needed.