Copy binary-tar.tar.gz to $PREFIX.rootfs.tar.gz if it exists.

debian/changelog

@@ -1,6 +1,7 @@
 livecd-rootfs (2.129) UNRELEASED; urgency=low
 
   * Disable zsync for ubuntu-touch images.
+  * Copy binary-tar.tar.gz to $PREFIX.rootfs.tar.gz if it exists.
 
  -- Colin Watson <cjwatson@ubuntu.com>  Fri, 03 May 2013 10:35:43 -0700
 

live-build/auto/build

@@ -301,6 +301,8 @@ if [ -e "binary/$INITFS/filesystem.dir" ]; then
 	(cd "binary/$INITFS/filesystem.dir/" && tar -c *) | \
 		gzip -9 --rsyncable > "$PREFIX.rootfs.tar.gz"
 	chmod 644 "$PREFIX.rootfs.tar.gz"
+elif [ -e binary-tar.tar.gz ]; then
+	cp -a binary-tar.tar.gz "$PREFIX.rootfs.tar.gz"
 fi
 
 # '--initramfs none' produces different manifest names.