title: RVM .ruby-gemset file does not switch gemsets
body: <p>Why doesn't rvm switch to @project_gemset when I cd into my project's directory? The gemset name in my .ruby-gemset file matches the name listed from rvm gemset list.</p>
  
  <pre>> cd project
  > ls -A
  .ruby-gemset
  > cat .ruby-gemset
  project_gemset
  > rvm gemset list
  
  gemsets for ruby-1.9.3-p392 (found in /Users/david/.rvm/gems/ruby-1.9.3-p392)
  => (default)
     global
     project_gemset</pre>