Comment 5 for bug 1704782

Note on test triggers:
s390x
https://jenkins.ubuntu.com/server/view/Virt/job/virt-in-release-s390x-a/19/consoleText
https://jenkins.ubuntu.com/server/view/Virt/job/virt-in-release-s390x-a/20/consoleText
https://jenkins.ubuntu.com/server/view/Virt/job/virt-in-release-s390x-a/21/consoleText
ppc64el
https://jenkins.ubuntu.com/server/view/Virt/job/virt-in-release-ppc64el-a/16/consoleText
https://jenkins.ubuntu.com/server/view/Virt/job/virt-in-release-ppc64el-a/17/consoleText

Always blocked on permission denied on s390x

s390x:
+ lxc exec testkvm-artful-from -- uvt-kvm create --template /root/guesttemplate.xml --password=ubuntu --ssh-public-key-file /home/ubuntu/.ssh/authorized_keys kvmguest-artful-normal release=artful arch=s390x label=daily
Warning: using --password from the command line is not secure and should be used for debugging only.
uvt-kvm: error: libvirt: internal error: process exited while connecting to monitor: 2017-07-13T23:24:42.730722Z qemu-system-s390x: -drive file=/var/lib/uvtool/libvirt/images/kvmguest-artful-normal.qcow,format=qcow2,if=none,id=drive-virtio-disk0: Could not open backing file: Could not open '/var/lib/uvtool/libvirt/images/x-uvt-b64-Y29tLnVidW50dS5jbG91ZC5kYWlseTpzZXJ2ZXI6MTcuMTA6czM5MHggMjAxNzA3MTE=': Permission denied

ppc:
+ lxc exec testkvm-artful-from -- uvt-kvm create --template /root/guesttemplate.xml --password=ubuntu --ssh-public-key-file /home/ubuntu/.ssh/authorized_keys kvmguest-artful-normal release=artful arch=ppc64el label=daily
Warning: using --password from the command line is not secure and should be used for debugging only.
uvt-kvm: error: libvirt: internal error: qemu unexpectedly closed the monitor: 2017-07-15T12:25:27.690715Z qemu-system-ppc64: -drive file=/var/lib/uvtool/libvirt/images/kvmguest-artful-normal.qcow,format=qcow2,if=none,id=drive-virtio-disk0: Could not open backing file: Could not open '/var/lib/uvtool/libvirt/images/x-uvt-b64-Y29tLnVidW50dS5jbG91ZC5kYWlseTpzZXJ2ZXI6MTcuMTA6cHBjNjRlbCAyMDE3MDcxMw==': Permission denied