autoupdate: Fix failing unittests.

BUG=None
TEST=./autoupdate_unittest.py

Change-Id: I2c496d29a417cd42cee530d473b9395c02978758
Reviewed-on: https://chromium-review.googlesource.com/268678
Reviewed-by: Gilad Arnold <garnold@chromium.org>
Commit-Queue: Bertrand Simonnet <bsimonnet@chromium.org>
Tested-by: Bertrand Simonnet <bsimonnet@chromium.org>
diff --git a/autoupdate_unittest.py b/autoupdate_unittest.py
index 4261f6f..eacd8c4 100755
--- a/autoupdate_unittest.py
+++ b/autoupdate_unittest.py
@@ -126,8 +126,9 @@
     au_mock = self._DummyAutoupdateConstructor()
 
     common_util.IsInsideChroot().AndReturn(True)
-    self._xbuddy._GetArtifact([''], board=self.test_board, lookup_only=True,
-        image_dir=None).AndReturn((latest_label, constants.TEST_IMAGE_FILE))
+    self._xbuddy._GetArtifact(
+        [''], board=self.test_board, lookup_only=True, image_dir=None,
+        version=None).AndReturn((latest_label, constants.TEST_IMAGE_FILE))
 
     au_mock.GenerateUpdateImageWithCache(
         os.path.join(self.static_image_dir, self.test_board, self.latest_dir,