test: fix race condition in TEST-80-NOTIFYACCESS

test: fix race condition in TEST-80-NOTIFYACCESS

In some cases systemd is faster to send the SIGHUP
than the script is to start the 'sleep' and background
it, so it never gets interrupted later and the test
is left hanging waiting for it.

[ 5028.410588] systemd[1]: Starting reload-timeout.service...
[ 5028.429544] reload-timeout.sh[165]: + set -o pipefail
[ 5028.429544] reload-timeout.sh[165]: + COUNTER=0
[ 5028.429841] reload-timeout.sh[165]: + trap sighup_handler SIGHUP
[ 5028.429841] reload-timeout.sh[165]: + export SYSTEMD_LOG_LEVEL=debug
[ 5028.429841] reload-timeout.sh[165]: + SYSTEMD_LOG_LEVEL=debug
[ 5028.429841] reload-timeout.sh[165]: + systemd-notify --ready
[ 5028.432891] systemd[1]: reload-timeout.service: Got notification message from PID 165: READY=1
[ 5028.432908] systemd[1]: reload-timeout.service: Changed start -> running
[ 5028.432983] systemd[1]: reload-timeout.service: Job 409 reload-timeout.service/start finished, result=done
[ 5028.432997] systemd[1]: Started reload-timeout.service.
[ 5028.433941] TEST-80-NOTIFYACCESS.sh[164]: Job for reload-timeout.service finished.
[ 5028.433941] TEST-80-NOTIFYACCESS.sh[164]: Got result done/Success for job reload-timeout.service.
[ 5028.433941] TEST-80-NOTIFYACCESS.sh[164]: Bus n/a: changing state RUNNING → CLOSED
[ 5028.436949] TEST-80-NOTIFYACCESS.sh[99]: + systemctl reload --no-block reload-timeout.service
[ 5028.444523] TEST-80-NOTIFYACCESS.sh[167]: Bus n/a: changing state UNSET → OPENING
[ 5028.444523] TEST-80-NOTIFYACCESS.sh[167]: sd-bus: starting bus by connecting to /run/systemd/private...
[ 5028.444523] TEST-80-NOTIFYACCESS.sh[167]: Bus n/a: changing state OPENING → AUTHENTICATING
[ 5028.444523] TEST-80-NOTIFYACCESS.sh[167]: Executing dbus call org.freedesktop.systemd1.Manager ReloadUnit(reload-timeout.service, replace)
[ 5028.444523] TEST-80-NOTIFYACCESS.sh[167]: Bus n/a: changing state AUTHENTICATING → RUNNING
[ 5028.445202] reload-timeout.sh[165]: + wait_for_signal
[ 5028.445586] reload-timeout.sh[169]: + sleep infinity
[ 5028.447285] reload-timeout.sh[165]: ++ sighup_handler
[ 5028.447285] reload-timeout.sh[165]: ++ echo hup1
[ 5028.444886] systemd[1]: reload-timeout.service: Trying to enqueue job reload-timeout.service/reload/replace
[ 5028.445228] systemd[1]: reload-timeout.service: Installed new job reload-timeout.service/reload as 491
[ 5028.445240] systemd[1]: reload-timeout.service: Enqueued job reload-timeout.service/reload as 491
[ 5028.446601] systemd[1]: reload-timeout.service: Service has no extensions to reload.
[ 5028.446799] systemd[1]: reload-timeout.service: Changed running -> reload-signal
[ 5028.446881] systemd[1]: Reloading reload-timeout.service...
[ 5028.451343] TEST-80-NOTIFYACCESS.sh[167]: Bus n/a: changing state RUNNING → CLOSED
[ 5028.452421] TEST-80-NOTIFYACCESS.sh[99]: + timeout 10 bash -c 'until [[ $(systemctl show reload-timeout.service -P SubState) == "reload-signal" ]]; do sleep .5; done'
[ 5028.460676] TEST-80-NOTIFYACCESS.sh[172]: Bus n/a: changing state UNSET → OPENING
[ 5028.460676] TEST-80-NOTIFYACCESS.sh[172]: sd-bus: starting bus by connecting to /run/systemd/private...
[ 5028.462029] TEST-80-NOTIFYACCESS.sh[172]: Bus n/a: changing state OPENING → AUTHENTICATING
[ 5028.462029] TEST-80-NOTIFYACCESS.sh[172]: Showing one /org/freedesktop/systemd1/unit/reload_2dtimeout_2eservice
[ 5028.463759] TEST-80-NOTIFYACCESS.sh[172]: Bus n/a: changing state AUTHENTICATING → RUNNING
[ 5028.470322] TEST-80-NOTIFYACCESS.sh[172]: Bus n/a: changing state RUNNING → CLOSED
[ 5028.472991] TEST-80-NOTIFYACCESS.sh[99]: + sync_in hup1
[ 5028.472991] TEST-80-NOTIFYACCESS.sh[99]: + read -r x
[ 5028.473839] reload-timeout.sh[165]: + wait 169
[ 5028.473996] TEST-80-NOTIFYACCESS.sh[99]: + test hup1 = hup1
[ 5028.473996] TEST-80-NOTIFYACCESS.sh[99]: + timeout 10 bash -c 'until [[ $(systemctl show reload-timeout.service -P SubState) == "reload-notify" ]]; do sleep .5; done'
[ 5038.477383] systemd[1]: TEST-80-NOTIFYACCESS.service: Failed with result 'exit-code'.

(note how the 'wait' is long after SIGHUP has been processed already)

Fixes https://github.com/systemd/systemd/issues/39581

Follow-up for ca8658120e1c9993bc05aa08dac2c74e618c2118