message: Disable setattr tracking for RNNs
  Exactly why they're so sensitive to it needs investigation
diff: @@ -442,7 +442,8 @@ class RNN(Layer):
  ```
  """
  - @trackable.no_automatic_dependency_tracking
  + _setattr_tracking = False
  +
  def __init__(self,
  cell,
  return_sequences=False,
  