$ gem list nokogiri
*** LOCAL GEMS ***
nokogiri (1.4.0, 1.3.3)
$ cat Gemfile
gem 'nokogiri', '1.4.0'
$ bundle install
Installing nokogiri (1.4.0) from system gems
Your bundle is complete!
$ bundle pack
The bundle is now locked. Use `bundle show` to list the gems in the environment.
Copying .gem files into vendor/cache
* nokogiri-1.4.0.gem
$ bundle install
Installing nokogiri (1.4.0) from .gem files at /private/tmp/bug-124/vendor/cache with native extensions
Your bundle is complete!