Make more build scripts barf when run as root.

src/scripts/build_image.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 build a bootable keyfob-based chromeos system image.
 # It uses debootstrap (see https://wiki.ubuntu.com/DebootstrapChroot) to
 # create a base file system. It then cusotmizes the file system and adds
 # Ubuntu and chromeos specific packages. Finally, it creates a bootable USB
 # image from the root fs.
 #
 # NOTE: This script must be run from the chromeos build chroot environment.
 #
 
 # Load common constants.  This should be the first executable line.
 # The path to common.sh should be relative to your script's location.
 . "$(dirname "$0")/common.sh"
 
-# Script must be run inside the chroot
 assert_inside_chroot
+assert_not_root_user
 
 DEFAULT_PKGLIST="${SRC_ROOT}/package_repo/package-list-prod.txt"
 
 # Flags
 DEFINE_integer build_attempt 1                                \
   "The build attempt for this image build."
 DEFINE_string output_root "${DEFAULT_BUILD_ROOT}/images"      \
   "Directory in which to place image result directories (named by version)"
 DEFINE_string build_root "$DEFAULT_BUILD_ROOT"                \
   "Root of build output"
@@ skipping 243 matching lines @@
 EOF
 
 OUTSIDE_OUTPUT_DIR="${EXTERNAL_TRUNK_PATH}/src/build/images/${IMAGE_SUBDIR}"
 echo "Done.  Image created in ${OUTPUT_DIR}"
 echo "To copy to USB keyfob, outside the chroot, do something like:"
 echo "  ./image_to_usb.sh --from=${OUTSIDE_OUTPUT_DIR} --to=/dev/sdb"
 echo "To convert to VMWare image, outside the chroot, do something like:"
 echo "  ./image_to_vmware.sh --from=${OUTSIDE_OUTPUT_DIR}"
 
 trap - EXIT