Should there be a "ruby" directory under "vendor" in a Rails 3 project?

Question

Is it normal to have the following directory structure under "vendor" in a Rail 3 project?

/vendor/ruby/1.8/bin  
/vendor/ruby/1.8/cache  
/vendor/ruby/1.8/doc  
/vendor/ruby/1.8/gems  
/vendor/ruby/1.8/specifications  

When I delete the "ruby" directory, and run "bundle update", the whole structure is recreated.
"gem env" yields nothing of interest:

RubyGems Environment:
  - RUBYGEMS VERSION: 1.3.7
  - RUBY VERSION: 1.8.7 (2010-04-19 patchlevel 253) [i686-darwin10.4.0]
  - INSTALLATION DIRECTORY: /opt/ruby-enterprise-1.8.7-2010.02/lib/ruby/gems/1.8
  - RUBY EXECUTABLE: /opt/ruby-enterprise-1.8.7-2010.02/bin/ruby
  - EXECUTABLE DIRECTORY: /opt/ruby-enterprise-1.8.7-2010.02/bin
  - RUBYGEMS PLATFORMS:
    - ruby
    - x86-darwin-10
  - GEM PATHS:
     - /opt/ruby-enterprise-1.8.7-2010.02/lib/ruby/gems/1.8
     - /Users/me/.gem/ruby/1.8
  - GEM CONFIGURATION:
     - :update_sources => true
     - :verbose => true
     - :benchmark => false
     - :backtrace => false
     - :bulk_threshold => 1000
  - REMOTE SOURCES:
     - http://rubygems.org/

Answer 1

It's a bundler system to recreate a entire Gem directory prefix by your ruby version. With that, you can change your ruby version easily and not reuse this gems. This directory is create only if you want "freeze" your gem in your application. If you don't freeze it you don't have this directory.