Currently, if someone navigates to /q/<change num> or a similar
pattern, they are redirected to the change, but the /q/<change num>
remains in the browser history, effectively messing up the back
button behavior (you hit back and it just redirects you forward
again).
Use window.location.replace to get the same behavior you would get
by using an HTTP redirect, which doesn’t break the back button.
Bug: Issue 7278
Change-Id: I352f741b170df477ccd267dc4d6bc951f0b8affa
6cabe1fc17