use link-dest to speed up kickstart dir creation

Author: nazunalika

sync/minor-release-sync-to-staging.sh

@@ -104,7 +104,7 @@ for ARCH in "${ARCHES[@]}"; do
     SOURCE="${STAGING_ROOT}/${CATEGORY_STUB}/${REV}/${REPO}/${ARCH}/os"
     TARGET="${STAGING_ROOT}/${CATEGORY_STUB}/${REV}/${REPO}/${ARCH}/kickstart"
     echo "Making golden kickstart directory"
-    rsync -vrlptDSH --chown=10004:10005 --progress --human-readable "${SOURCE}/" "${TARGET}"
+    rsync -vrlptDSH --chown=10004:10005 --progress --human-readable --link-dest="${SOURCE}" "${SOURCE}/" "${TARGET}"
   done
 done