It has recently come to my attention that those of you with private and Jetpack-enabled blogs using my script to redirect to the classic editor may have noticed that the script no longer works; you end up in an infinite loop. This is because the link that the script scrapes from the page has been rendered useless. Those using the bookmarklet are also affected.
I’ll see what I can do, but considering I had this issue when I first made the script, finding a solution will be difficult. However, I do have an idea that might work, but it still won’t work for Jetpack sites whose site root is different from the installation root. To anyone who can figure it out, please leave a comment or submit a patch (work from the dev branch).