How to fake fix broken persistent objects in ZODB

I have a Zope / Plone website with some old objects created by Products.feedfeeder and they store (for some weird reason) instances of BeautifulSoup objects. These objects were created with BeautifulSoup 3 and the installed version of BS is 4, which moved its classes in the bs4.* namespace. Now, running full-sweep searches in the site or a full catalog reindex fails because of these, now broken, objects.

My solution, because I didn't care for those stored BeautifulSoup objects, was to fake the BeautifulSoup module and patch it into sys.modules:

class NavigableString(unicode):
    def __new__(cls):
        return unicode.__new__(cls)

    def __getstate__(self):
        return self.__dict__

class Tag(object):
    def __getstate__(self):
        return self.__dict__

class BeautifulSoup(object):
    def __getstate__(self):
        return self.__dict__

class fake_bs3(object):
    NavigableString = NavigableString
    Tag = Tag
    BeautifulSoup = BeautifulSoup

import sys
sys.modules['BeautifulSoup'] = fake_bs3