message: Avoid infinite recursion in IpuOptimizer.get_slot
  Summary:
  Now calls the wrapped optimizer's get_slot as it should.
  TF2.4 Only.
  Fixes T50680
  Test Plan: CI.
  Reviewers: samuelh, jackh, #tensorflow, #framework_ip_review_-_any_oss_or_third-party_code_use_has_been_approved
  Maniphest Tasks: T50680
diff: @@ -49,7 +49,7 @@ class IpuOptimizer(OptimizerV2):
  for the wrapped optimizer.
  Args:
  - name: The name of the atrribute to set.
  + name: The name of the attribute to set.
  value: The value to set.
  """
  # Delegate setting hyperparameter to inner optimizer if the attribute does
  @@ -235,7 +235,7 @@ class IpuOptimizer(OptimizerV2):
  var: A variable to look up.
  slot_name: The name of the slot.
  """
  - return self.get_slot(var, slot_name)
  + return self._opt.get_slot(var, slot_name)
  def add_slot(self, var, slot_name, initializer="zeros"):
  """
  