We are not really interested in the return code and error messages from
dbus-monitor after killing it, so ignore them to avoid undesired
autopkgtest failures.
Follow-up for commit 3de342799c.
is-active return code isn't the correct way to verify a service is
fully stopped; instead use show --property=ActiveState to verify it
is 'inactive'
This also could use the text output of is-active, but (per manpage)
the show command is "intended to be used whenever computer-parsable
output is required."
systemctl is-active returns non-zero even while the service is
'deactivating', but not actually stopped, which allows the testcase
to fail intermittently on slow machines, if the service hasn't
actually stopped before reaching the check to verify the service
stopped.
For example:
$ systemctl is-active systemd-timesyncd
active
$ timedatectl set-ntp false ; systemctl is-active systemd-timesyncd ; echo $?
deactivating
3
So the test code which does:
$ while systemctl is-active --quiet systemd-timesyncd; do sleep 1; done
will never actually perform that sleep.
