Possible recursion in PageContentErrorHandler with untranslated pages
If you specify a page as the content source of an error page in the new sites module, there are situations in which repeating redirects (and hopefully a timeout) can occur. In my case, my site has several languages (strict mode), but the error page wasn't translated to all of them. This would trigger a 404 when fetching the error page for a translated site, which itself would trigger another 404 and so on.
I'll provide a possible patch soon via Gerrit.