Only calculate checksums, when there are files to monitor. (#2776)

target/scripts/helpers/change-detection.sh

@@ -73,5 +73,9 @@ function _monitored_files_checksums
   do
     [[ -f "${FILE}" ]] && CHANGED_FILES+=("${FILE}")
   done
-  sha512sum -- "${CHANGED_FILES[@]}"
+
+  if [[ -n ${CHANGED_FILES:-} ]]
+  then
+    sha512sum -- "${CHANGED_FILES[@]}"
+  fi
 }

test/mail_smtponly.bats

@@ -1,11 +1,7 @@
 load 'test_helper/common'
 
 function setup_file() {
-  local PRIVATE_CONFIG
-  PRIVATE_CONFIG=$(duplicate_config_for_container .)
-
   docker run --rm -d --name mail_smtponly \
-    -v "${PRIVATE_CONFIG}":/tmp/docker-mailserver \
     -v "$(pwd)/test/test-files":/tmp/docker-mailserver-test:ro \
     -e SMTP_ONLY=1 \
     -e PERMIT_DOCKER=network \