Verify that SCRIPTS_DIR exists in build_image.

build_image

Index: build_image
diff --git a/build_image b/build_image
index 2dc7c7887bc20feeaadd4dc89f2f4e80a059cf66..d56edac157863f4be37d6330d683885f9b18ad5d 100755
--- a/build_image
+++ b/build_image
@@ -9,17 +9,17 @@
 # the given target's root with binary packages turned on. This script will
 # build the Chrome OS image using only pre-built binary packages.
 
-# --- BEGIN COMMON.SH BOILERPLATE ---
 # Load common CrOS utilities.  Inside the chroot this file is installed in
 # /usr/lib/crosutils.  Outside the chroot we find it relative to the script's
 # location.
 find_common_sh() {
-  local common_paths=(/usr/lib/crosutils $(dirname "$(readlink -f "$0")"))
+  local common_paths=(/usr/lib/crosutils $(dirname "$0"))
   local path
 
   SCRIPT_ROOT=
   for path in "${common_paths[@]}"; do
-    if [ -r "${path}/common.sh" ]; then
+    local common="${path}/common.sh"
+    if ([ -r "${common}" ] && . "${common}" && [ -d "${SCRIPTS_DIR}" ]); then
       SCRIPT_ROOT=${path}
       break
     fi
@@ -27,8 +27,7 @@ find_common_sh() {
 }
 
 find_common_sh
-. "${SCRIPT_ROOT}/common.sh" || (echo "Unable to load common.sh" && exit 1)
-# --- END COMMON.SH BOILERPLATE ---
+. "${SCRIPT_ROOT}/common.sh" || ! echo "Unable to load common.sh" || exit 1
 
 # Load functions and constants for chromeos-install
 [ -f /usr/lib/installer/chromeos-common.sh ] && \