Add a script to test guessing release notes manually

It is easier this way to figure out why things go awry that way. This
script can be used like this:

	./test-guess-relnote.js git-for-windows/git#4164

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

test-guess-relnote.js

@@ -0,0 +1,21 @@
+#!/usr/bin/env node
+
+(async () => {
+    // Expect a URL
+    const url = process.argv[2]
+    const match = url.match(/^https:\/\/github\.com\/([^/]+)\/([^/]+)\/(?:issues|pulls?)\/(\d+)\/?$/)
+    if (!match) throw new Error(`Unhandled URL: ${url}`)
+    const [, owner, repo, number ] = match
+
+    const githubApiRequest = require('./GitForWindowsHelper/github-api-request')
+    const issue = await githubApiRequest(
+        console,
+        null,
+        'GET',
+        `/repos/${owner}/${repo}/issues/${number}`
+    )
+
+    const { guessReleaseNotes } = require('./GitForWindowsHelper/component-updates')
+    const guessed = await guessReleaseNotes(issue)
+    console.log(JSON.stringify(guessed, null, 2))
+})().catch(console.log)