[dataimport] Fix method signature
Since d4bd28d5fca8, _storage_handler expect 4 args.
grafted from b089858c49a2806b6ea8a7ee66773436701e947c (3.22)
related to #9177565.
# -*- coding: utf-8 -*-
# copyright %(year)s %(author)s, all rights reserved.
# contact %(author-web-site)s -- mailto:%(author-email)s
#
%(long-license)s
"""%(distname)s entity's classes"""