message: Better error message for ResourceVariable.set_shape
diff: @@ -680,6 +680,10 @@ class ResourceVariable(variables.Variable):
  """Unsupported."""
  raise NotImplementedError("ResourceVariable does not implement _ref()")
  + def set_shape(self, shape):
  + """Unsupported."""
  + raise NotImplementedError("ResourceVariable does not implement set_shape()")
  +
  @staticmethod
  def _OverloadOperator(operator): # pylint: disable=invalid-name
  """Defer an operator overload to `ops.Tensor`.
  