Comment 9 for bug 1654025

I fixed ("fixed"?) this by removing the use of 'lxc exec ... -- sleep 3600' as a synchronisation method in favour of checking /proc/uptime directly - when that goes backwards, we've rebooted.

I don't know why that didn't work - I didn't reproduce the misbehavour when using lxd directly myself outside of autopkgtest. I also don't know why it seemed happened on trusty only. Possibly a slightly slower/faster 'reboot'?

Can't link the branch for some reason, but https://git.launchpad.net/~laney/autopkgtest/+git/autopkgtest/commit/?id=ed8f754790e3a03cee467d3985680f93ac0e2c63 - trying to find out the best way to get that reviewed/landed in autopkgtest upstream.