common: log loopback detaches

We want to find the culprit loopback device which isn't detatching on
crbug.com/1141907. We might as well log our cleanup actions anyway, and
this will allow us to see the last loopback processed in production.

BUG=chromium:1141907
TEST=just a log message
BRANCH=None
Signed-off-by: George Engelbrecht <engeg@google.com>
Change-Id: I126efceae4f67993069675c23f6c4af61c7e5667
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/2514561
Reviewed-by: LaMont Jones <lamontjones@chromium.org>
diff --git a/scripts/image_signing/common.sh b/scripts/image_signing/common.sh
index f1fd3ef..9541ca0 100644
--- a/scripts/image_signing/common.sh
+++ b/scripts/image_signing/common.sh
@@ -120,6 +120,7 @@
 cleanup_loopbacks() {
   local line
   while read -r line; do
+    info "Cleanup: detaching ${line}"
     loopback_detach "${line}" 2>/dev/null
   done <"${TEMP_LOOP_LIST}"
   rm -f "${TEMP_LOOP_LIST}"