[e10s on] GM_xmlhttpRequest - does not show login prompt

[janekptacijarabaci]

Ad #2048 (comment)... continued.

Confirmed on:
Firefox Aurora 40.0a2 (2015-05-29)
Firefox Nightly 41.0a1 (2015-05-29)
GM 3.2

Gist: https://gist.github.com/janekptacijarabaci/8b969e5f48a305d91fd7

[e10s off]:
Result:
GM_xmlhttpRequest() 2: status: 200 statusText: OK (show login prompt)
GM_xmlhttpRequest() 3: status: 200 statusText: OK

Reloading page (F5):
GM_xmlhttpRequest() 2: status: 200 statusText: OK (does not show login prompt)
GM_xmlhttpRequest() 3: status: 200 statusText: OK

[e10s on]:
(does not show login prompt)
Result:
GM_xmlhttpRequest() 2: status: 401 statusText: Authorization Required
GM_xmlhttpRequest() 3: status: 401 statusText: Authorization Required

XMLHttpRequest() - OK (show login prompt)

[janekptacijarabaci]

See also https://developer.mozilla.org/en-US/Firefox/Multiprocess_Firefox/Limitations_of_frame_scripts#XUL_and_browser_UI

[arantius]

Confirmed, I hate e10s SO MUCH. Also, simpler reproduction script for my future reference:

// ==UserScript==
// @name        GM_xhr HTTP Auth Test
// @include     http://localhost/*
// @exclude     http://localhost/auth*
// @grant       GM_xmlhttpRequest
// ==/UserScript==

GM_xmlhttpRequest({
  method: 'GET',
  url: "http://localhost/auth/",
  onload: function(xhr) {
    dump('script '+xhr.responseText.substr(0, 128).replace(/\n/g, ' ')+'\n');
  },
});

I have basically no idea how to address this or even why it might be happening.

[arantius]

https://bugzilla.mozilla.org/show_bug.cgi?id=1217876