This also updates all dependent functionality, including modelform_factory
and modelformset_factory, and the generic views `ModelFormMixin`,
`CreateView` and `UpdateView` which gain a new `fields` attribute.
Translate before passing in the variables (i.e. close the bracket earlier).
If you translate after passing in the variables the translated value will contain the actual values for 'url' and 'site' and will therefore not be translated.
(I'm not actually using django's flatpages, but I ran into this apparent error when doing a global grep on my own project)