If you can suggest code for linux that finds the users preferred webbrowser,
I would really like to see it.  The web browser selection already works well
in OSX (it invokes "open") and in windows (where it invokes "start").  But
the linux web browser selection logic is lacking.

Note, however, that as a work-around, you can say:

   fossil setting web-browser WHATEVER -global

Do the above once, and be forevermore happy.