Comment 8 for bug 531599

I have been able to test a potential fix for this problem. The unmap() function is responsible for tearing apart the device maps created by the kpartx commands. Those are created by the map_partitions() function.

While tearing down the device maps created by the parted command, which is invoked in the partition() function might be better done by a callback in the partition() function, the patch is simpler by adding to the existing unmap() which is a callback from map_partition, which is invoked sequentially after partition() in hypervisor.py.

Please let me know if the patch in the proposed branch is unacceptable.