There are two problems with qvm-run -a:
1) even with -q flag, it spits to stdout (actually, "xl create" does it), and
this garbage is received by rpc client
2) even with -q flag, it steals input (actually, "qrexec ... wait for session")
These two can be manually fixed (by passing /dev/null appropriately); hovewer,
this is prone to disaster if qvm-run is enhanced/broken later.
We could do
if is_domain_running() ; then
run qrexec client
else
qvm-run -a domain true </dev/null >/dev/null
run qrexec client
fi
which looks safer; but is_domain_running() is a bit expensive even in "running"
case - we need to xl_context.list_domains anyway.
Gotta decide on one of these.
