apparmor-tumbler: use set -e

Debian Policy §10.4 says "Every script should use set -e or check
the exit status of every command", which is just generally good
advice.

Reviewed-by: Philip Withnall <philip.withnall@collabora.co.uk>
Signed-off-by: Simon McVittie <simon.mcvittie@collabora.co.uk>
Differential Revision: https://phabricator.apertis.org/D3478

apparmor/tumbler/test-tumbler

 #!/bin/bash
 # vim: tw=0
 
+set -e
+
 TEST_DIR=$(cd $(dirname $0); pwd; cd - &>/dev/null)
 # We want to use the pre-existing session bus.
 export LAUNCH_DBUS="no"
 
-"${TEST_DIR}"/run-aa-test "${TEST_DIR}"/tumbler.normal.expected "${TEST_DIR}"/tumbler normal
-"${TEST_DIR}"/run-aa-test "${TEST_DIR}"/tumbler.malicious.expected "${TEST_DIR}"/tumbler malicious
+exit_status=0
+
+"${TEST_DIR}"/run-aa-test "${TEST_DIR}"/tumbler.normal.expected "${TEST_DIR}"/tumbler normal || exit_status=$?
+"${TEST_DIR}"/run-aa-test "${TEST_DIR}"/tumbler.malicious.expected "${TEST_DIR}"/tumbler malicious || exit_status=$?
+
+exit "$exit_status"