The value of a `GM_xmlhttpRequest` response cookie is incorrect

[double-beep]

Consider this script:

// ==UserScript==
// @name         Test script
// @version      0.1
// @author       You
// @match        https://example.com
// @grant        GM_xmlhttpRequest
// ==/UserScript==

(function() {
    GM_xmlhttpRequest({
        url: 'https://stackoverflow.com',
        onload: a => console.log(a.responseHeaders)
    });
})();

which runs on https://example.com making a request to Stack Overflow's homepage and printing the response headers of that request.

The problem with the script, that although I'm logged in to Stack Overflow, the value of the acct cookie (the only one used for authentication) is shown as t&s, while it should be t=oq9zBs0.....&s=66SXR3f%2fb......

I've noticed this problem occurs since I've updated Tampermonkey to v5.2.6196.

[derjanb]

Thanks for reporting. Should be at 5.2.6197 (crx|xpi in review)

Please download the crx file linked above and drag and drop it to the extensions page chrome://extensions (after you've enabled 'Developer Mode').