Preferred Applications does not update default browser properly (xdg-open)

Submitted by Sorinello

Assigned to Nick Schermer

Link to original bug (#11976)

Description

Steps to reproduce:

1. have Firefox
2. install Chrome
3. now, when running xdg-open http://google.com, you'll get Chrome
4. go to all settings -> preferred application -> select Firefox (if it wasn't already selected).
5. run again xdg-open http://google.com => you'll get Chrome
6. optionally, I tried to swtich to Chrome then back to Firefox from Preferred Applications. Same result.

If I have Firefox set as my default Browser, I'd expect the URL to be opened by Firefox. This affects several programs which rely on xdg-open command. One example is IRC xchat2.

Version: 4.12.0