message: Avoid calling K.learning_phase() when not necessary in Dropout layer since it instantiates a placeholder_with_default, which is not supported by TPU compilation.
diff: @@ -130,6 +130,7 @@ class Dropout(Layer):
  return nn_ops._get_noise_shape(inputs, self.noise_shape) # pylint: disable=protected-access
  def call(self, inputs, training=None):
  + original_training_value = training
  if training is None:
  training = K.learning_phase()
  @@ -141,7 +142,7 @@ class Dropout(Layer):
  dropped_inputs,
  lambda: array_ops.identity(inputs))
  # EagerTensor object has no attribute _uses_learning_phase
  - if not context.executing_eagerly() and training is K.learning_phase():
  + if not context.executing_eagerly() and original_training_value is None:
  output._uses_learning_phase = True # pylint: disable=protected-access
  return output
  