I was able to reproduce this. As MAAS only talks to libvirt via ssh, giving it the parameters to create a VM, and the fact that this is not an issue with other storage backends, I believe this is a libvirt bug as libvirt is ultimately calling the command to create the volume storage.
I was able to reproduce this. As MAAS only talks to libvirt via ssh, giving it the parameters to create a VM, and the fact that this is not an issue with other storage backends, I believe this is a libvirt bug as libvirt is ultimately calling the command to create the volume storage.