Comment 29 for bug 939161

> I don't need nothing else than a piece of code that fix this bug

Edit /usr/share/pulseaudio/alsa-mixer/paths/analog-output-headphones.conf and comment out the Jack detect session, so it looks like this:

; [Jack Headphone]
; required-any = any

That turns off jack detection for your machine.
Restart pulseaudio afterwards (pulseaudio -k ).