Like login-import's ChatGPT window, only the page was routed, so the
window GitHub's device sign-in opens loaded the real site (304 requests
to github.githubassets.com in one full Chromium run). It wasn't red here
(10 at once in Chromium: 0/20 failed), but its outcome rested on pages
the test doesn't control. Chromium and WebKit, en and zh: pass, and no
request went past the two window URLs, which the route answers.