Used by qubes.StartApp so that we can override distribution-provided
.desktop files. The mechanism is introduced to run gnome-terminal
with --wait option, so that it's compatible with DispVMs.
FixesQubesOS/qubes-issues#2581.
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
Both Archlinux and Fedora 29 have guidelines to point explicitly at
/usr/bin/python2 where it expect python2.
Also, do not use env.
FixesQubesOS/qubes-issues#4027
This is especially important for qubes-desktop-run used inside DispVM.
The DesktopAppInfo.launch() method returns after just launching the
application. In DispVM case it worked by a coincidence - because the
launched application was keeping stdin/out open, which also prevented
DispVM killing. Use DesktopAppInfo.launch_uris_as_manager which at least
allows to learn PIDs of spawned processes, to track them manually.
This still doesn't fix gnome-terminal issue, or any other application
using either DBus activation, or any other client-server model. But at
least fix basic apps like firefox and xterm.
FixesQubesOS/qubes-issues#3213
Since we have proper python package, use it instead of hacky one-file
package. This will ease installation and packaging, including switching
to python3.
