I followed examples from existing tests such as virsh_{destroy | domid | reboot | shutdown | start | vncdisplay | dominfo | dommemstat | domstate | list} to use the complete_uri method.  If 'VirshConnectBack" is the proper way, then perhaps all tests should be converted to use it, but I only see it used in virsh_{migrate_multi_vms | vcpuinfo}.  Perhaps conversion to a standard interface needs to be a different task...