$NetBSD: patch-ah,v 1.2 2008/04/13 06:01:59 jlam Exp $

--- lib/rubygems.rb.orig	2008-04-09 17:18:31.000000000 -0400
+++ lib/rubygems.rb
@@ -213,7 +213,13 @@ module Gem
   ##
   # The path where gem executables are to be installed.
 
-  def self.bindir(install_dir=Gem.dir)
+  def self.bindir(install_dir=Gem.dir, install_root=nil)
+    unless install_root.nil?
+      install_root_path = Pathname.new install_root
+      install_dir_path = Pathname.new install_dir
+      install_dir_path = install_dir_path.relative_path_from install_root_path
+      install_dir = install_dir_path.expand_path File::SEPARATOR
+    end
     return File.join(install_dir, 'bin') unless
       install_dir.to_s == Gem.default_dir
     Gem.default_bindir