It seems like that's one of Evan Weaver's many projects. I've added him to this conversation. Perhaps if you're willing to take over maintainership you two can work something out! His email is evan [at] cloudbur.st if you want to contact him outside of this thread, or feel free to use it as you see fit.
I have no problem with your fork, but let's call it has_many_polymorphs_2 or something so that people don't send me your bug reports. :-) I don't maintain it anymore. I can yank the old one if you want.