Observed on http://en.wikipedia.beta.wmflabs.org/wiki/Main_Page
Sequence of events:
http://login.wikimedia.beta.wmflabs.org/wiki/Special:CentralAutoLogin/checkLoggedIn?type=script&wikiid=enwiki&proto=http 301 Moved Permanently Location:http://wikimediafoundation.org/wiki/Special:CentralAutoLogin/checkLoggedIn?type=script&wikiid=enwiki&proto=http http://wikimediafoundation.org/wiki/Special:CentralAutoLogin/checkLoggedIn?type=script&wikiid=enwiki&proto=http 307 Internal Redirect Location:https://wikimediafoundation.org/wiki/Special:CentralAutoLogin/checkLoggedIn?type=script&wikiid=enwiki&proto=http https://wikimediafoundation.org/wiki/Special:CentralAutoLogin/checkLoggedIn?type=script&wikiid=enwiki&proto=http 404 Not Found