message: Fix typo in Tensorflow control_flow_ops_py_test.
  The test would fall back to GPU:0 when unable to find a GPU. This should be CPU.
diff: @@ -1753,7 +1753,7 @@ class ControlFlowTest(test.TestCase):
  def _testWhileGrad_ColocateGradients(self, colocate):
  gpu_dev_name = test.gpu_device_name() if test.is_gpu_available(
  - ) else "/device:GPU:0"
  + ) else "/device:CPU:0"
  graph = ops.Graph()
  with graph.as_default():
  