TensorFlow: fix python3 gfile_test. Fixes #1146.

Change: 114880791

tensorflow/python/platform/default/gfile_test.py

@@ -222,10 +222,10 @@ class FunctionTests(_BaseTest, googletest.TestCase):
 
   def testOpen(self):
     with gfile.Open(self.tmp + "test_open", "wb") as f:
-      f.write("foo")
+      f.write(b"foo")
     with gfile.Open(self.tmp + "test_open") as f:
       result = f.readlines()
-    self.assertEqual([b"foo"], result)
+    self.assertEqual(["foo"], result)
 
 if __name__ == "__main__":
   googletest.main()