AU: make mk_memento_images not change rootfs

cros_generate_update_payload

 #!/bin/bash
 
 # Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # Script to generate a Chromium OS update for use by the update engine.
 # If a source .bin is specified, the update is assumed to be a delta update.
 
 # Load common constants.  This should be the first executable line.
@@ skipping 149 matching lines @@
 else
   echo "Generating full update"
   
   trap cleanup INT TERM EXIT
   DST_KERNEL=$(extract_partition_to_temp_file "$FLAGS_image" 2)
   patch_kernel "$FLAGS_image" "$DST_KERNEL"
   DST_ROOT=$(extract_partition_to_temp_file "$FLAGS_image" 3)
   
   GENERATOR="$(dirname "$0")/mk_memento_images.sh"
 
-  "$GENERATOR" "$DST_KERNEL" "$DST_ROOT"
+  CROS_GENERATE_UPDATE_PAYLOAD_CALLED=1 "$GENERATOR" "$DST_KERNEL" "$DST_ROOT"
   mv "$(dirname "$DST_KERNEL")/update.gz" "$FLAGS_output"
   
   trap - INT TERM EXIT
   cleanup noexit
   echo "Done generating full update."
 fi