The 'browse' command determines if I have launchy installed in the following fashion:

helper :has_launchy? do |blk|
  begin
    gem 'launchy'
    require 'launchy'
    blk.call
  rescue Gem::LoadError
    STDERR.puts "Sorry, you need to install launchy: `gem install launchy`"
  end  
end

Except that in some cases, I may have installed launchy through other means, such as using a package (e.g. the Debian/Ubuntu policy favors packages over gems, so this will apply when launchy is eventually packaged, or even right now using the most excellent thwarted/gem2deb ). In those cases, commenting
gem 'launchy'
above suffices to get 'gh browse' running.