move the nexus rootfs tarball around instead of copying it

debian/changelog

@@ -1,8 +1,9 @@
 livecd-rootfs (2.100) UNRELEASED; urgency=low
 
   * clean up the userdata dir
+  * move the tarball around instead of copying it
 
- -- Oliver Grawert <ogra@chromebook>  Mon, 19 Nov 2012 19:48:42 +0100
+ -- Oliver Grawert <ogra@ubuntu.com>  Mon, 19 Nov 2012 19:48:42 +0100
 
 livecd-rootfs (2.99) raring; urgency=low
 

live-build/auto/build

@@ -382,8 +382,9 @@ if [ "$SUBARCH" = "ac100" ] || [ "$SUBARCH" = "nexus7" ]; then
 
 		# roll the android rootfs images
 		mkdir -p userdata
-		cp $PREFIX.rootfs.tar.gz userdata/rootfs.tar.gz
+		mv $PREFIX.rootfs.tar.gz userdata/rootfs.tar.gz
 		make_ext4fs -l 6G -s $PREFIX.img-$FLAVOUR userdata/
+		mv userdata/rootfs.tar.gz $PREFIX.rootfs.tar.gz
 		ln -sf "$PREFIX.img-$FLAVOUR" "$PREFIX.img"
 	fi