Comment 8 for bug 1002113

In case this helps someone in the future: xdg-open thinks you're on gnome, so uses the gnome settings. I got the following:

% gvfs-mime --query x-scheme-handler/http
Default application for 'x-scheme-handler/http': firefox.desktop
Registered applications:
 firefox.desktop
 google-chrome-beta.desktop
Recommended applications:
 firefox.desktop
 google-chrome-beta.desktop

Fixed with:

% gvfs-mime --set x-scheme-handler/http google-chrome-beta.desktop
Set google-chrome-beta.desktop as the default for x-scheme-handler/http

% gvfs-mime --set x-scheme-handler/https google-chrome-beta.desktop
Set google-chrome-beta.desktop as the default for x-scheme-handler/https