message: Copy of fix for optimizers v2.
diff: @@ -334,8 +334,8 @@ class OptimizerV2(checkpointable.CheckpointableBase):
  reduced_grads = merge_grads(grads_and_vars)
  grads_and_vars = zip(reduced_grads, var_list)
  - with ops.init_scope():
  self._prepare()
  + with ops.init_scope():
  self._create_slots(var_list)
  update_ops = []
  