Monkeypatching rails 2.x to load Mongrel with bundler

boot.rb

# ...8<...

Rails.boot!

# see http://gembundler.com/rails23.html to make Bundler work with Rails 2.x (tested with 2.1, 2.2 and 2.3)

# bundler with rails 2.x prevents finding mongrel_rails in PATH
if $0 == "script/server"
  # ensure active_support is loaded
  require 'active_support'

  module MongrelFix
    puts "Patching load() for mongrel_rails"
    # Patching load from active_support (watching out for recursion)
    def self.included(base)
      base.class_eval do
        unless defined? load_without_mongrel_fixed
          alias_method :load_without_mongrel_fixed, :load_without_new_constant_marking
          define_method :load_with_mongrel_fixed do |file, *extras|
            if file == 'mongrel_rails'
              puts "Fixing mongrel_rails filename path"
              # Using bundled mongrel_rails
              file = %x[bundle show mongrel].strip() + '/bin/mongrel_rails'
            end
            load_without_mongrel_fixed(file, *extras)
          end
          alias_method :load_without_new_constant_marking, :load_with_mongrel_fixed
        end
      end
    end

  end unless defined? load_with_mongrel_fixed
  Object.instance_eval { include MongrelFix }

end