[Pharo-project] Found senders of #isSystemDefined in Nile

Hi, I've found a few senders of #isSystemDefined when trying to run the pharo dev test suite, and I don't know what is the expected behavior. I've read in: http://www.mail-archive.com/pharo-project@lists.gforge.inria.fr/msg12075.htm... the idea is to remove the message and all it's senders, but I don't know why is used here in Nile. The senders are in NSSmartRefStream, inside of #uniClassInstVarsRefs:, #uniClasesDo: and #beginInstance:size: Any hint on this will be appreciated. Cheers, Mariano.