message: serializer.Serializer: Fix logs.
diff: @@ -196,7 +196,7 @@ namespace elle
  friend
  std::ostream&
  - operator <<(std::ostream& s, current_name& c)
  + operator <<(std::ostream& s, current_name const& c)
  {
  auto name = c._serializer.current_name();
  if (!name.empty())
  