Fix test_image_unittest

BUG=None
TEST=the unittest does not fail anymore

Change-Id: Iadb083a9bc2ee6eed9f7dcfa57ba88b8a000c57e
Reviewed-on: https://chromium-review.googlesource.com/208792
Tested-by: Yu-Ju Hong <yjhong@chromium.org>
Reviewed-by: Don Garrett <dgarrett@chromium.org>
Commit-Queue: Yu-Ju Hong <yjhong@chromium.org>
diff --git a/scripts/test_image_unittest.py b/scripts/test_image_unittest.py
index 8ecd48c..841e270 100755
--- a/scripts/test_image_unittest.py
+++ b/scripts/test_image_unittest.py
@@ -6,9 +6,11 @@
 """Unit tests for the functions in test_image."""
 
 import os
+import sys
 import tempfile
 import unittest
 
+sys.path.insert(0, os.path.abspath('%s/../..' % os.path.dirname(__file__)))
 from chromite.cbuildbot import constants
 from chromite.cros.tests import image_test
 from chromite.lib import cros_build_lib