Search in USB for savefiles when booting from CD

Puppy forum member shinobar provided this.
see http://www.murga-linux.com/puppy/viewtopic.php?p=780277#780277

woof-code/boot/initrd-tree0/init

@@ -882,10 +882,15 @@ if [ -s /tmp/flag-usb-ready ];then #110710 has stuff in it if usb drives exist.
  touch /tmp/OPTICALDRIVES0 #fix
  [ "$OPTICALDRIVES0" ] && echo "$OPTICALDRIVES0" > /tmp/OPTICALDRIVES0 #fix
  echo "ALLDRVS=$ALLDRVS " >> /tmp/puppy-file-search.log
-
+ PUPSFS_OPT=""
+ if [ "$PUPSFS" ]; then
+   FS=$(echo $PUPSFS | cut -s -f2 -d',')
+   echo $FS | grep -q -E 'iso9660|udf' && PUPSFS_OPT=$PUPSFS && PUPSFS=""
+ fi
  if [ "$VMLINUZ" = "" -o "$PUPSFS" = "" -o "$SAVEPART" = "" ];then
   search_func usb
  fi
+ [ "$PUPSFS" ] || PUPSFS=$PUPSFS_OPT
 fi
 
 cp -f /tmp/PUPSAVES /tmp/PUPSAVES-complete #101127 for debugging.