Fix Failbot sending auth (#22396)

Part of #1063

lib/failbot.js

@@ -5,6 +5,23 @@ export default class FailBot {
     this.app = app
     this.haystackURL = haystackURL
     this.headers = headers
+
+    // Since we're using `node-fetch` we can't rely on it deconstructing the
+    // basic authentication credentials from the URL (e.g.
+    // https://user:pass@failbotdomain/path) because `node-fetch` will always
+    // strip it. See https://github.com/node-fetch/node-fetch/issues/1330
+    // and it's not a bug.
+    // The correct thing is to extract it manually and add an `Authorization`
+    // header based on it from the URL.
+    const url = new URL(this.haystackURL)
+    const { username, password } = url
+    if (username || password) {
+      this.headers.Authorization = `Basic ${Buffer.from(`${username}:${password}`).toString(
+        'base64'
+      )}`
+    } else {
+      console.warn(`The haystack URL does not contain authentication credentials`)
+    }
   }
 
   /**