Fix unittest

Author: reyoung

python/paddle/v2/fluid/tests/test_registry.py

@@ -28,4 +28,4 @@ def test_registry_layer(self):
         exe = fluid.Executor(place)
         X = np.random.random((10, 10)).astype("float32")
         mean_out = exe.run(feed={"X": X}, fetch_list=[output])
-        self.assertAlmostEqual(np.mean(X), mean_out)
+        self.assertAlmostEqual(np.mean(X), mean_out[0])