message: Add a test for TPUStrategy LSTM model.
diff: @@ -41,6 +41,7 @@ from tensorflow.python.framework import tensor_util
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import control_flow_ops
  from tensorflow.python.ops import math_ops
  +from tensorflow.python.ops import resource_variable_ops
  from tensorflow.python.ops import variable_scope as vs
  from tensorflow.python.tpu import device_assignment as device_assignment_lib
  from tensorflow.python.tpu import tpu
  @@ -547,7 +548,8 @@ class TPUExtended(distribute_lib.StrategyExtendedV1):
  return output
  def _update(self, var, fn, args, kwargs, group):
  - assert isinstance(var, values.TPUMirroredVariable)
  + assert isinstance(var, values.TPUMirroredVariable) or isinstance(
  + var, resource_variable_ops.ResourceVariable)
  if values._enclosing_tpu_context() is not None: # pylint: disable=protected-access
  if group:
  return fn(var, *args, **kwargs)
  @@ -567,7 +569,8 @@ class TPUExtended(distribute_lib.StrategyExtendedV1):
  return values.update_regroup(self, self._device_map, updates, group)
  def read_var(self, var):
  - assert isinstance(var, values.TPUMirroredVariable)
  + assert isinstance(var, values.TPUMirroredVariable) or isinstance(
  + var, resource_variable_ops.ResourceVariable)
  return var.read_value()
  def _local_results(self, val):
  