build-gnu.sh: correct path suggestion for fetch-gnu.sh

util/build-gnu.sh

@@ -37,7 +37,7 @@ path_GNU="$("${READLINK}" -fm -- "${path_GNU:-${path_UUTILS}/../gnu}")"
 if test ! -f "${path_GNU}/configure"; then
     echo "Could not find the GNU coreutils (expected at '${path_GNU}')"
     echo "Download them to the expected path:"
-    echo "  (cd '${path_GNU}' && fetch-gnu.sh ) "
+    echo " (mkdir -p '${path_GNU}' && cd '${path_GNU}' && bash '${path_UUTILS}/util/fetch-gnu.sh')"
     echo "You can edit fetch-gnu.sh to change the tag"
     exit 1
 fi