Comment 4 for bug 1652934

>>> I found several failures on nova side, for example http://paste.openstack.org/show/593621/, so it will be good if Nova team take a look at this, too.

it must be ok: it's a valid error in Nova when we try to create a live snapshot without support from the guest OS (a qemu agent must be running in the guest), we then retry using a simpler approach - https://github.com/openstack/nova/blob/master/nova/virt/libvirt/driver.py#L1898-L1913