Comment 4 for bug 611362

I just heard about a case of this happening on Ubuntu 12.10. I suspect it's a bug in setuptools or distutils or ubuntu's patching of same, not zope.interface; can someone comment on what mechanism ZI uses to include the 'common' package? I don't see it in setup.cfg, or a manifest file... I am guessing there's some setuptools magic which is supposed to make it get included.