'Given a new slug to be assigned to this document, check
whether there is an existing, non-redirect, Document at that
slug in this locale. Any redirect existing there will be
deleted.
This is necessary since page moving is a background task, and
a Document may come into existence at the target slug after
the move is requested.'

def _move_conflicts(self, new_slug):

    existing = None
    try:
        existing = Document.objects.get(locale=self.locale, slug=new_slug)
    except Document.DoesNotExist:
        pass
    if (existing is not None):
        if existing.is_redirect:
            existing.delete()
        else:
            raise Exception('Requested    move    would    overwrite    a    non-redirect    page.')
