#define MATCH_BROWSER "^(([^:/?#]+)://)?([^/?#])([^?#]*)(\\?([^#]*))?(#(.*))?"

This RegEx is horribly written and matches nearly everything possible. If I knew what the entirety of the goal is for it I would offer a correction.

It's used both in 0.3.106 and 0.6.0, however I'm running 0.3.106 and that's where it's giving me a headache currently, trying to implement a custom protocol for use in Chrome.
No matter what, because this line *ALWAYS* matches, all exo-open will do is open another Chrome window. It will *NEVER* default to gnome-open like it should.

(Note: The only things that won't match are things that start with one of /?# which is, of course, nothing you'd ever pass to exo-open)

Honestly I'd suggest only opening http:// and https:// links in the browser. Sure browsers handle other stuff, but that's all they're really meant for.