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__()'