[web] on logout, use the base_url argument of build_url instead of hacking the request to get proper url. This fix a bug on site with http/https versions: the session cookie is badly removed on logout

"""pre 3.6 bw compat"""
# pylint: disable-msg=W0614,W0401
from warnings import warn
warn('moved to cubicweb.mttransforms', DeprecationWarning, stacklevel=2)
from cubicweb.mttransforms import *