fix basename invocation

stack.sh

@@ -741,7 +741,7 @@ if [[ "$ENABLED_SERVICES" =~ "g-reg" ]]; then
     for image_url in ${IMAGE_URLS//,/ }; do
         # Downloads the image (uec ami+aki style), then extracts it.
         IMAGE_FNAME=`basename "$image_url"`
-        IMAGE_NAME=`basename -s .tar.gz "$IMAGE_FNAME"`
+        IMAGE_NAME=`basename "$IMAGE_FNAME" .tar.gz`
         if [ ! -f $FILES/$IMAGE_FNAME ]; then
             wget -c $image_url -O $FILES/$IMAGE_FNAME
         fi