message: Use ObjectIdentity...() in Keras backend.py for Tensors
diff: @@ -1091,7 +1091,7 @@ def freezable_variable(value, shape=None, name=None):
  global _FREEZABLE_VARS
  if graph not in _FREEZABLE_VARS:
  - _FREEZABLE_VARS[graph] = weakref.WeakSet()
  + _FREEZABLE_VARS[graph] = object_identity.ObjectIdentityWeakSet()
  _FREEZABLE_VARS[graph].add(x)
  return x
  