This reverts commit 3145b32f.

Otherwise, ERP5 site setup fails while importing erp5_core/ToolTemplateItem/portal_transforms.xml.

/SR/parts/erp5/product/ERP5/Document/BusinessTemplate.py(930)_importFile()
    928         # FIXME: Why not use the importXML function directly? Are there any BT5s
    929         # with actual .zexp files on the wild?
--> 930         obj = connection.importFile(file_obj, customImporters=customImporters)
    931       self._objects[obj_key] = obj
    932

ipdb> file_obj
<_io.BufferedReader name='/SR/parts/erp5/product/ERP5/bootstrap/erp5_core/ToolTemplateItem/portal_transforms.xml'>
...
> /SR/develop-eggs/zodbpickle-2.0.0+slapospatched001-py3.8-linux-x86_64.egg/zodbpickle/pickle_3.py(995)decode_string()
    993                 return value
    994         else:
--> 995             return value.decode(self.encoding, self.errors)
    996
    997     def load_string(self):

ipdb> p value
b'\x00\x00\x00\x00\x00\x00\x00\x80'

otherwise we will have an Exception in Python 3 while importing a Business Template,
if a new portal type and its documents exist in the same Business Template.

while importing a content file, like *.js...

(BusinessTemplate.py)
  try:
    setattr(obj, property_name, data)
  except BrokenModified:
    obj.__Broken_state__[property_name] = data # <-- !!!
    obj._p_changed = 1

obj.__Broken_state__ access here also raises BrokenModified.

while importing an XML file...

(ZODB/broken.py)
  def __new__(class_, *args):
    result = object.__new__(class_) # <-- !!!
    result.__dict__['__Broken_newargs__'] = args
    return result

we get an exception 'TypeError: object.__new__(Portal Type) is not safe, use Base.__new__()'