look one step later to account for one extra function call in dot; fixes unit test

theano/gof/tests/test_compute_test_value.py

@@ -244,7 +244,7 @@ class TestComputeTestValue(unittest.TestCase):
                 # Get traceback
                 tb = sys.exc_info()[2]
                 # Get frame info 3 layers up
-                frame_info = traceback.extract_tb(tb)[-4]
+                frame_info = traceback.extract_tb(tb)[-5]
                 # We should be in the "fx" function defined above
                 assert os.path.split(frame_info[0])[1] == 'test_compute_test_value.py'
                 assert frame_info[2] == 'fx'