This caused problems with our tests suite where we were using a logged
in browser session and actually acting as a different user.
(imported from commit 73b8cb39d5d669e682fbacf2f7e574c228885c2f)
If you don't have a cookie or basic auth and the request looks like
a top-level page in the browser, redirect to the login page.
(imported from commit fc1bcb1080591522bd1b694664255f7049a5d443)