Fixes an issue where the `/login?new_link=true` and
`/login?expired=true` pages were not displayed to users because of an
extra `/` after `/login`. Instead, users were redirected to
`/login?forward=%2Flogin%2F%3Fnew_link%3Dtrue` and
`/login?forward=%2Flogin%2F%3F expired%3Dtrue` respectively.