make initialize_copy private
|Target version:||next minor|
|ruby -v:||2.1.0dev||Backport:||1.9.3: UNKNOWN, 2.0.0: UNKNOWN|
it was discussed with nobu that initialize_copy should be a private method, and any cases where it's public is considered a bug.
when i asked matz he said, it sounds good and ok to experiment with this change in trunk.