[Findit] Record error if swarming task completes with exit_code as 2.

appengine/findit/waterfall/test/swarming_util_test.py

Index: appengine/findit/waterfall/test/swarming_util_test.py
diff --git a/appengine/findit/waterfall/test/swarming_util_test.py b/appengine/findit/waterfall/test/swarming_util_test.py
index b4252b797ffbc13016c0a0cc4d1dfd98304bc1ae..9ac70162be055625c6fae6c7efc83247ef89c711 100644
--- a/appengine/findit/waterfall/test/swarming_util_test.py
+++ b/appengine/findit/waterfall/test/swarming_util_test.py
@@ -578,4 +578,8 @@ class SwarmingUtilTest(wf_testcase.WaterfallTestCase):
     self.assertIsNone(swarming_util.GetTagValue(tags, 'c'))
 
   def testGenerateIsolatedDataOutputsrefNone(self):
-    self.assertEqual({}, swarming_util._GenerateIsolatedData(None))
+    self.assertEqual({}, swarming_util._GenerateIsolatedData(None))
+
+  def testFetchOutputJsonInfoFromIsolatedServerReturnNone(self):
+    self.assertIsNone(swarming_util._FetchOutputJsonInfoFromIsolatedServer(
+        None, self.http_client))