sanity-check: show what we're doing before we do it

Signed-off-by: Simon McVittie <simon.mcvittie@collabora.co.uk>
Differential Revision: https://phabricator.apertis.org/D3651

common/sanity-check

@@ -24,6 +24,8 @@ fail () {
     echo "TEST_RESULT:fail:$tag:$*" >&2
 }
 
+set -x
+
 # This is just for information, so we ignore the exit status. Minimal
 # images might legitimately not have these tools.
 systemd-cgls -al --no-pager || :