Cleanup LRF from ordering garbage. Upgrades plone.app.multilingual 2.0a3 to 2.0.1

configure.zcml

<configure
    xmlns="http://namespaces.zope.org/zope"
    xmlns:browser="http://namespaces.zope.org/browser"
    xmlns:zcml="http://namespaces.zope.org/zcml">
  <browser:page
      class=".upgradelrf.Upgrade"
      for="plone.app.multilingual.content.lrf.LanguageRootFolder"
      name="lp-migrate-lrf"
      permission="cmf.ManagePortal"
  />
</configure>

upgradelrf.py

# -*- coding: utf-8 -*-
from zope.publisher.browser import BrowserView

blacklist = [
    'acl_users',
    'archetype_tool',
    'caching_policy_manager',
    'content_type_registry',
    'error_log',
    'HTTPCache',
    'MailHost',
    'mimetypes_registry',
    'plone_utils',
    'portal_actionicons',
    'portal_actions',
    'portal_archivist',
    'portal_atct',
    'portal_calendar',
    'portal_catalog',
    'portal_controlpanel',
    'portal_css',
    'portal_diff',
    'portal_discussion',
    'portal_factory',
    'portal_form_controller',
    'portal_groupdata',
    'portal_groups',
    'portal_historiesstorage',
    'portal_historyidhandler',
    'portal_interface',
    'portal_javascripts',
    'portal_languages',
    'portal_memberdata',
    'portal_membership',
    'portal_metadata',
    'portal_migration',
    'portal_modifier',
    'portal_password_reset',
    'portal_properties',
    'portal_purgepolicy',
    'portal_quickinstaller',
    'portal_referencefactories',
    'portal_registration',
    'portal_registry',
    'portal_repository',
    'portal_setup',
    'portal_skins',
    'portal_tinymce',
    'portal_transforms',
    'portal_types',
    'portal_uidannotation',
    'portal_uidgenerator',
    'portal_uidhandler',
    'portal_undo',
    'portal_url',
    'portal_view_customizations',
    'portal_workflow',
    'RAMCache',
    'reference_catalog',
    'ResourceRegistryCache',
    'translation_service',
    'uid_catalog',
    # here all the LRF ids need to be listed
    'de',
    'en',
]


class Upgrade(BrowserView):

    def __call__(self):
        result = ['Check for garbage in ordering....']
        order = self.context.getOrdering()
        to_remove = []
        for oid in order._order():
            if oid in blacklist:
                to_remove.append(oid)
        for oid in to_remove:
            order.notifyRemoved(oid)
            result.append('{0} removed from pos+order'.format(oid))
        return '\n'.join(result)