There's a race condition in the sysuser test where it may try to read
entries from the journal before they are available. Fix it by adding a
`journalctl --sync` call.
BugLink: https://bugs.launchpad.net/bugs/1776654
prepare_testdir ${f%.input}
cp $f $TESTDIR/usr/lib/sysusers.d/test.conf
systemd-sysusers --root=$TESTDIR 2> /dev/null
+ journalctl --sync
journalctl -t systemd-sysusers -o cat | tail -n1 > $TESTDIR/tmp/err
if ! diff -u $TESTDIR/tmp/err ${f%.*}.expected-err; then
echo "**** Unexpected error output for $f"