Properly kill dbus-monitor subprocess
While we call kill on it, it does not actually do what it says it does.
See how Hustle does it, https://gitlab.freedesktop.org/bustle/bustle/-/blob/22f454058f203ab18e735348900151f27708cb59/c-sources/pcap-monitor.c#L875
I tried to reimplement it on Rust, and while it kills dbus-monitor
, flatpak-spawn
is still running.