• Fix: When constructing dummy requests for pages with no routable URL, fall back on a hostname from ALLOWED_HOSTS and finally 'localhost', to avoid 'Invalid HTTP_HOST header' errors on preview when DEBUG=False.
• Fix: Ensure that url_path is populated when previewing a newly created page, to avoid unnecessarily taking the above fallback.
• Fix: Deleting an item from an InlinePanel, then generating a validation error on saving, no longer causes the deleted item to confusingly reappear with an error of its own.