1. wait=False isn't supportet together with localcmd (explicit, or
implicit via 'input') - qrexec-client refuses such combination
2. When using localcmd, qrexec-client exists as soon as the local command
terminates, not necessary remote. This may not be desired effect when
used with wait=True (the default), so do not use localcmd in such a
case
Found while debugging tests for qubes.USBAttach/qubes.USBDetach - with
wait=True broken, there were a lot of race conditions.
Related to QubesOS/qubes-issues#531
046149e0f4