Fix problem with mod_image_for_test leaving dangling chroot ref

src/scripts/mod_image_for_test.sh

 #!/bin/bash
 
 # Copyright (c) 2009 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 modify a keyfob-based chromeos system image for testability.
 
 # Load common constants.  This should be the first executable line.
 # The path to common.sh should be relative to your script's location.
@@ skipping 32 matching lines @@
 cleanup_rootfs_mounts() {
   # Occasionally there are some daemons left hanging around that have our
   # root image file system open. We do a best effort attempt to kill them.
   PIDS=`sudo lsof -t "${ROOT_FS_DIR}" | sort | uniq`
   for pid in ${PIDS}
   do
     local cmdline=`cat /proc/$pid/cmdline`
     echo "Killing process that has open file on our rootfs: $cmdline"
     ! sudo kill $pid  # Preceded by ! to disable ERR trap.
   done
+  if [[ -d "${ROOT_FS_DIR}/modify_scripts" ]]; then
+    echo "Cleaned up modify_scripts mount"
+    ! sudo umount "${ROOT_FS_DIR}/modify_scripts"
+  fi
 }
 
 cleanup_rootfs_loop() {
   sudo umount "${LOOP_DEV}"
   sleep 1  # in case $LOOP_DEV is in use
   sudo losetup -d "${LOOP_DEV}"
 }
 
 cleanup() {
   # Disable die on error.
@@ skipping 27 matching lines @@
   if [ "$SURE" != "y" ]; then
     echo "Ok, better safe than sorry."
     exit 1
   fi
 else
   echo "Modifying image ${FLAGS_image} for test..."
 fi
 
 MOD_SCRIPTS_ROOT="${GCLIENT_ROOT}/src/scripts/mod_for_test_scripts"
 sudo mkdir -p "${ROOT_FS_DIR}/modify_scripts"
+
 sudo mount --bind "${MOD_SCRIPTS_ROOT}" "${ROOT_FS_DIR}/modify_scripts"
 
 # Run test setup script inside chroot jail to modify the image
 sudo chroot "${ROOT_FS_DIR}" "/modify_scripts/test_setup.sh"
 
 sudo umount "${ROOT_FS_DIR}/modify_scripts"
 sudo rmdir "${ROOT_FS_DIR}/modify_scripts"
 
 cleanup
 trap - EXIT