title: where are my gems installed with rbenv?
body: <p>I use rbenv and bundler, I want open the installed rails gem and insert some debug codes. So I run 'bundle show rails' in a rails project, I get '~/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/rails-3.2.11', but there is nothing in this directory. </p>