message: Clarify error encountered when serializing critical_section_executions is a warning.
diff: @@ -439,9 +439,10 @@ def add_collection_def(meta_graph_def, key, graph=None,
  else:
  getattr(col_def, kind).value.extend([x for x in collection_list])
  except Exception as e: # pylint: disable=broad-except
  - logging.warning("Error encountered when serializing %s.\n"
  + logging.warning("Issue encountered when serializing %s.\n"
  "Type is unsupported, or the types of the items don't "
  - "match field type in CollectionDef.\n%s", key, str(e))
  + "match field type in CollectionDef. Note this is a warning "
  + "and probably safe to ignore.\n%s", key, str(e))
  if key in meta_graph_def.collection_def:
  del meta_graph_def.collection_def[key]
  return
  