test: correctly fail when system is borked

In certain situations, the systemctl commands may fail (e.g. due to
missing shared libraries), but the 'script' continues and creates a
/testok file, marking the test incorrectly as passed. Let's fix this and
bail out immediately when a command exits with a non-zero exit code.

test/TEST-01-BASIC/test.sh

@@ -24,7 +24,7 @@ Description=Testsuite service
 After=multi-user.target
 
 [Service]
-ExecStart=/bin/sh -x -c 'systemctl --state=failed --no-legend --no-pager > /failed ; systemctl daemon-reload ; echo OK > /testok'
+ExecStart=/bin/sh -e -x -c 'systemctl --state=failed --no-legend --no-pager > /failed ; systemctl daemon-reload ; echo OK > /testok'
 Type=oneshot
 EOF