Nova-compute is curerntly generating a backtrace when trying to nova
boot a VM. The backtrace is described in the bug log. Bind-mounting
/sys/fs/cgroup:/sys/fs/cgroup in the libvirt container resolves the
problem.
Change-Id: I5a56b61fd260728fb76e19bcbdf403b80a4ec5a6
Closes-Bug: #1490326