bundler-bundle-itself.diff

diff --git a/lib/bundler/cli.rb b/lib/bundler/cli.rb
index 3314db0..16e6498 100644
--- a/lib/bundler/cli.rb
+++ b/lib/bundler/cli.rb
@@ -91,6 +91,8 @@ module Bundler
       "Don't update the existing gem cache."
     method_option "quiet", :type => :boolean, :banner =>
       "Only output warnings and errors."
+    method_option "no-auto-update", :type => :boolean, :banner =>
+      "Do not bundle itself"
     def install(path = nil)
       opts = options.dup
       opts[:without] ||= []
diff --git a/lib/bundler/installer.rb b/lib/bundler/installer.rb
index 4a18b2c..fa79a0e 100644
--- a/lib/bundler/installer.rb
+++ b/lib/bundler/installer.rb
@@ -21,6 +21,14 @@ module Bundler
       # Ensure that BUNDLE_PATH exists
       FileUtils.mkdir_p(Bundler.bundle_path)
 
+      if !options['no-auto-update'] && bundler = specs.detect { |spec| spec.name == 'bundler' }
+        bundler.source.fetch(bundler) if bundler.source.respond_to?(:fetch)
+        bundler.source.install(bundler)
+        Bundler.ui.info ""
+        Bundler.ui.info "Auto-updated. Reloading..."
+        exec *[$0, ARGV, '--no-auto-update'].flatten
+      end
+
       # Must install gems in the order that the resolver provides
       # as dependencies might actually affect the installation of
       # the gem.