message: Replace != with is check
diff: @@ -415,7 +415,7 @@ class TPUReplicateContext(control_flow_ops.XLAControlFlowContext):
  for index in xrange(len(op.inputs)):
  x = op.inputs[index]
  real_x = self.AddValue(x)
  - if real_x != x:
  + if real_x is not x:
  op._update_input(index, real_x) # pylint: disable=protected-access
  if external_control_inputs:
  