Let's use the newly gained feature of `busctl` and start is as a
Type=notify unit, which should make sure the unit is started only after
`busctl` is on the bus listening for messages.
This should help with a race spotted in CIs, where we continued too
early after starting `busctl monitor` and miss the emitted signals:
[ 10.914831] testsuite-45.sh[694]: + systemd-run --unit busctl-monitor.service --service-type=exec busctl monitor --json=short '--match=type='\''signal'\'',sender=org.freedesktop.timesync1,member='\''PropertiesChanged'\'',path=/org/free>
[ 11.064365] systemd[1]: Starting busctl-monitor.service...
[ 11.064903] systemd[1]: Started busctl-monitor.service.
[ 11.065192] testsuite-45.sh[740]: Running as unit: busctl-monitor.service; invocation ID: ee44a9d713c34b9a97e3e7f6f4fffe77
...
[ 11.069255] testsuite-45.sh[694]: + timedatectl ntp-servers ntp99 10.0.0.1
[ 11.077140] systemd-timesyncd[728]: Network configuration changed, trying to establish connection.
[ 11.077461] testsuite-45.sh[694]: + assert_networkd_ntp ntp99 10.0.0.1
...
[ 11.087418] testsuite-45.sh[694]: + assert_timesyncd_signal '2023-11-08 16:28:48.861455' LinkNTPServers 10.0.0.1
...
[ 11.095543] testsuite-45.sh[694]: + for _ in {0..9}
[ 11.095543] testsuite-45.sh[694]: + journalctl -q '--since=2023-11-08 16:28:48.861455' -p info _SYSTEMD_UNIT=busctl-monitor.service --grep .
[ 11.193258] systemd-journald[375]: Received client request to sync journal.
[ 11.112424] testsuite-45.sh[694]: + sleep .5
[ 11.160318] dbus-daemon[465]: [system] Connection :1.56 (uid=0 pid=741 comm="/usr/bin/busctl monitor --json=short --match=type=") became a monitor.
Resolves: #29923
41e4ce06fe shortened existing sleeps, which resulted in the check being
sometimes done before the property had a chance to update. Let's do what
what we do with the rest of the checks and retry it a couple of times.
Resolves: #29923
As in their current form they didn't work at all:
systemd-timesyncd[190115]: Assertion 's' failed at src/libsystemd/sd-event/sd-event.c:3058, function sd_event_source_set_enabled(). Ignoring.
systemd-timesyncd[190115]: Failed to reenable system ntp server change event source!
systemd-timesyncd[190115]: Failed to enable ntp server defer event, ignoring: Invalid argument
This was also pointed out in the post-merge review [0].
Let's address this together with the rest of the comments, and add
some tests to make sure everything works as it should.
Resolves: #28770
Follow-up to: 8f1c446
[0] 8f1c446979 (r124147466)
(The one case that is left unchanged is '< <(subcommand)'.)
This way, the style with no gap was already dominant. This way, the reader
immediately knows that ' < ' is a comparison operator and ' << ' is a shift.
In a few cases, replace custom EOF replacement by just EOF. There is no point
in using someting like "_EOL" unless "EOF" appears in the text.
