message: Replace set with  ObjectIdentity...Set to prepare eq behavior change
diff: @@ -31,6 +31,7 @@ from tensorflow.python.training.tracking import base as trackable
  from tensorflow.python.util import deprecation
  from tensorflow.python.util import function_utils
  from tensorflow.python.util import nest
  +from tensorflow.python.util import object_identity
  from tensorflow.python.util import tf_contextlib
  from tensorflow.python.util.tf_export import tf_export
  @@ -587,7 +588,7 @@ def _add_elements_to_collection(elements, collection_list):
  collection_list = nest.flatten(collection_list)
  for name in collection_list:
  collection = ops.get_collection_ref(name)
  - collection_set = set(collection)
  + collection_set = object_identity.ObjectIdentitySet(collection)
  for element in elements:
  if element not in collection_set:
  collection.append(element)
  