``pyramid.i18n.Localizer.pluralize`` run using that domain/locale
combination raised an inscrutable "translations object has no attr 'plural'
error. Now, instead it "works" (it uses a germanic pluralization by
default). This is not the "right" thing really (it's nonsensical to try to
pluralize something without translations for that locale/domain available),
but it matches the behavior of ``pyramid.i18n.Localizer.translate`` so it's
at least consistent; see #235.