One more undefined variable fix for set -u

debian/changelog

@@ -1,3 +1,9 @@
+livecd-rootfs (1.139) UNRELEASED; urgency=low
+
+  * One more undefined variable fix for set -u
+
+ -- Steve Langasek <steve.langasek@ubuntu.com>  Wed, 21 Jul 2010 11:10:44 +0200
+
 livecd-rootfs (1.138) maverick; urgency=low
 
   * Don't go overboard with the downgrading of packages; this probably caused

livecd.sh

@@ -155,6 +155,7 @@ IMAGEFORMAT="squashfs"
 # name is "ppa", don't omit it
 PPA=""
 APT_SOURCE=""
+FORCE_YES=""
 
 while getopts :d:e:i:I:m:S:s:a:A:f:p name; do case $name in
     d)  STE=$OPTARG;;