This part of GIO library isn't suitable for short-lived processes (the
call is done asynchronously and may not reach the application before
qubes-desktop-run process is terminated). To fix this, implement dbus
activation manually, synchronously.
While at it, implement waiting for application to terminate (useful in
DispVM), by waiting for its dbus name to disappear.
dbus-python API isn't particularly nice, but don't switch to completely different
library as a stable update.
FixesQubesOS/qubes-issues#2449
75e54cd5ef