'XMLHttpRequest.prototype.getResponseHeader()' issue in scriptlet and redirect #2518

Prerequisites

• I verified that this is not a filter list issue. Report any issues with filter lists or broken website functionality in the uAssets issue tracker.
• This is not a support issue or a question. For support, questions, or help, visit /r/uBlockOrigin.
• I performed a cursory search of the issue tracker to avoid opening a duplicate issue.
• The issue is not present after disabling uBO in the browser.
• I checked the documentation to understand that the issue I am reporting is not normal behavior.

I tried to reproduce the issue when...

• uBO is the only extension.
• uBO uses default lists and settings.
• using a new, unmodified browser profile.

Description

A specific URL where the issue occurs.

https://piquark6046.github.io/testpage/XMLResponseHeader/

Steps to Reproduce

The step to reproduce is attached in the video.

piquark6046.github.io##+js(no-xhr-if, adsbygoogle.js)
||pagead2.googlesyndication.com/pagead/js/adsbygoogle.js$redirect=googlesyndication_adsbygoogle.js
@@||pagead2.googlesyndication.com/pagead/js/adsbygoogle.js

Expected behavior

• XMLHttpRequest.prototype.status returns 200.
• XMLHttpRequest.prototype.getResponseHeader('content-length') returns a digit number.
• XMLHttpRequest.prototype.getResponseHeader('expires') returns a date and time.
• XMLHttpRequest.prototype.getAllResponseHeaders() returns response header of a request.

Actual behavior

When a $redirect filter is applied:

• XMLHttpRequest.prototype.status returns 0.
• XMLHttpRequest.prototype.getResponseHeader('content-length') returns anull.
• XMLHttpRequest.prototype.getResponseHeader('expires') returns null.
• XMLHttpRequest.prototype.getAllResponseHeaders() returns an empty string.

When a scriptlet filter is applied:

• All methods and property return empty data.

uBO version

1.47.2

Browser name and version

Mozilla Firefox Developer Edition 111.0b7

Operating System and version

Ubuntu 22.10