fix 404 for wget

acme.sh

@@ -1609,7 +1609,7 @@ _get() {
       $_WGET --user-agent="$USER_AGENT" --header "$_H5" --header "$_H4" --header "$_H3" --header "$_H2" --header "$_H1" -O - "$url"
     fi
     ret=$?
-    if [ "$_ret" = "8" ]; then
+    if [ "$ret" = "8" ]; then
       ret=0
       _debug "wget returns 8, the server returns a 'Bad request' respons, lets process the response later."
     fi