moiristo/deep_cloneable — pull request #14 by zozi (2012-04-12 16:42:08+00:00)
Title: Rails2.x 3.0

A fix for handling has_and_belongs_to_many associations.
This only clones the join table rows, not the associated objects.
However, I believe habtm is currently broken, since there were no tests that used it, and I could not get it to work at all because of errors in determining the reverse association. You might use this as a starting point, and change the cloning behavior.