title: "gem install bundler --version=0.8.1" doesn't install the bundle executable
body: <p>When trying to install Bundler 0.8.1 on Ubuntu machine, it install fine but the executable "bundle" is no where to be seen. Other gems install successfully, including their executables.</p>
  
  <p>using: <code>gem install bundler --version=0.8.1</code></p>
  
  <pre><code>RubyGems Environment:
  - RUBYGEMS VERSION: 1.3.7
  - RUBY VERSION: 1.8.7 (2009-06-12 patchlevel 174) [i486-linux]
  - INSTALLATION DIRECTORY: /home/ahammad/gems
  - RUBY EXECUTABLE: /usr/bin/ruby1.8
  - EXECUTABLE DIRECTORY: /home/ahammad/gems/bin
  - RUBYGEMS PLATFORMS:
  - ruby
  - x86-linux
  - GEM PATHS:
   - /home/ahammad/gems
  - GEM CONFIGURATION:
   - :update_sources =&gt; true
   - :verbose =&gt; true
   - :benchmark =&gt; false
   - :backtrace =&gt; false
   - :bulk_threshold =&gt; 1000
   - :sources =&gt; ["http://gems.rubyforge.org/", "http://gem1.gilt.com"]
  - REMOTE SOURCES:
   - http://gems.rubyforge.org/
  </code></pre>
  
  <p>Path <code>/home/ahammad/gems/bin</code> has been added to <code>PATH</code>, the problem is there is no bundle exe.</p>
  
  <p>Any ideas?</p>