If you’re a web-developer, you probably came across the pretty useful Firefox add-on „LiveHTTPHeaders„, which allows you to monitor, replay and even modify the headers your browser sends to the webserver. Unfortunately, there’s been a bug in it for now more than a year that prevents you from modifying HTTP POST requests – you always get a „Request entity too large!“ response, due to duplicate Content-Type headers.
After having to patch the add-on for several times, (because every „new“ version of LiveHTTPHeaders breaks it again, which doesn’t happen too often, fortunately) I decided to upload a quick fix for this problem.