append self-fork icon on Hatena::Let for UserScript

hatenalet-selffork.user.js

// ==UserScript==
// @name        Hatena::Let self fork
// @namespace   http://noromanba.flavors.me
// @description append self-fork icon on Hatena::Let for UserScript
// @include     http://let.hatelabo.jp/*
// @grant       none
// @noframes
// @run-at      document-end
// @version     2017.3.2.0
// @homepage    https://gist.github.com/noromanba/f5bc6779c3c3005d6d106da5aa624990
// @downloadURL https://gist.github.com/noromanba/f5bc6779c3c3005d6d106da5aa624990/raw/hatenalet-selffork.user.js
// @contributor taizooo     http://let.hatelabo.jp/taizooo/let/gYC-ydPttrvedg
// @contributor noromanba   http://let.hatelabo.jp/noromanba/let/gYC-x6_02LnWEg (Fork of)
// @license     MIT License https://nrm.mit-license.org/2017
// @author      noromanba   http://noromanba.flavors.me
// @icon        https://upload.wikimedia.org/wikipedia/commons/thumb/b/b9/BSicon_uetABZg%2B4.svg/128px-BSicon_uetABZg%2B4.svg.png
// ==/UserScript==

// Icon (PD by YLSS)
// https://commons.wikimedia.org/wiki/File%3ABSicon_uetABZg%2B4.svg

// Devel
// https://gist.github.com/noromanba/f5bc6779c3c3005d6d106da5aa624990

// Bookmarklet
// http://let.hatelabo.jp/noromanba/let/gYC-x6_02LnWEg


(() => {
  'use strict';

  const edit = document.body.querySelector('a.edit-link[href*="/let.edit"]');
  if (!edit) return;

  // fork URL syntax
  // http://let.hatelabo.jp/<USER_ID>/let.fork?code_id=<LET_ID>
  //  http://let.hatelabo.jp/<USER_ID>/let/<LET_ID>
  // http://let.hatelabo.jp/<USER_ID>/let.fork?rev_id=<REV_ID>
  //  http://let.hatelabo.jp/<USER_ID>/let/<LET_ID>/rev/<REV_ID>
  const fork = edit.cloneNode();
  fork.pathname = edit.pathname.replace(/\.edit$/, '.fork');
  fork.textContent = 'Fork';
  // TBD change image

  edit.parentNode.appendChild(fork);
})();

This no longer works because the fork link has been replaced with a form that includes a authenticity_token field. I don't think there is any way around that from the browser.
I now use https://github.com/defunkt/gist from the CLI to:

• # Define your original gist url (I have to use the ssh url to get it to work for my credential-helper)
  original_url="git@gist.github.com:f5bc6779c3c3005d6d106da5aa624990.git"
• # Create a new gist
  url="$(date | gist -f temp)"
• # Clone it
  git clone $url; cd $(basename $url)
• # Add the original gist as a remote and fetch it
  git remote add alt $original_url; git fetch alt
• # Check out the original
  git reset --hard alt/master
• # Push to the new gist
  git push -f origin master

Note: the # are in there so you can copy-pasta the whole block into the terminal 😉