Edition problems with a public page that becomes a private page
If the author of a public page transforms it into a private page, other users shouldn't be able to modify this page or to revert it to a previous version, if they are not co-authors. But they can, there's a in problem in this case.
If the page has been created as a private page, becomes a public page and after, becomes a private page, it works.
TODO: a page created as a public page and transformed into a private page must be modified only by its co-authors, not by all users.