Comment 3 for bug 876788

To duplicate the user experience
open ~/.local/share/applications/mimeapps.list

Under the [Default Applications] section add
inode/directory=nautilus-folder-handler.desktop

In the [Added Associations ] make sure some .desktop is on a similar line - to create least amount of personal trouble use this
inode/directory=firefox.desktop;

log out/in & try any of the above scenario's

related to this bug that affected 11.10
 Bug 797000