Comment 17 for bug 1899180

Ok the results over the weekend look promising, tested on arm64:
- unmodified 6/31 fails
- new 0/31 fails

But when checking the good cases in detail what I found was that in all
cases the domain was considered running, but then continuously (= not a race) failed to enter namespace. I've had 9 cases where this happened, so it wasn't a one off.

libvirt-lxc still isn't the most important case, so reworking the test still is right, but this seems to have a semi-real-issue on armhf (not reproducible anywhere else).
I'd like to avoid to mask errors on other architectures by e.g. re-starting the domain if it failed - therefore I'd not want to remove the test or unconditionally accept it as flaky, but maybe it is ok to do so on armhf only.

With that fixed up I'll do some retries on hirsute@arm64 (to see if it detects ans skip/pass correctly now) and the same backported to bionic@amd64 (for the service restart issue).