update capacity after truncation

Author: crschardt

pack_image.sh

@@ -45,6 +45,7 @@ if [[ ${shrink,,} = y* ]]; then
         fi            
         echo "Shrinking image from ${initial_image_size} to ${image_size} bytes."
         truncate -s "${image_size}" "${image}"
+        losetup --set-capacity "${loopdev}"
         if [[ "${part_type}" == "gpt" ]]; then
             # use sgdisk to fix the secondary GPT after truncation 
             sgdisk -e "${image}"