title: Rails 2.3-style plugins and deprecation warnings running task in Heroku
body: <p>I'm upgrading to Rails 3.2, and running rake db:migrate gives me several errors of the form:</p>
  
  <blockquote>
    <p>DEPRECATION WARNING: You have Rails 2.3-style plugins in vendor/plugins! Support for these plugins will be removed in Rails 4.0. Move them out and bundle them in your Gemfile, or fold them in to your app as lib/myplugin/* and config/initializers/myplugin.rb. See the release notes for more on this: <a href="http://weblog.rubyonrails.org/2012/01/04/rails-3-2-0-rc2-has-been-released" rel="noreferrer">http://weblog.rubyonrails.org/2012/01/04/rails-3-2-0-rc2-has-been-released</a>. (called from  at /app/Rakefile:7)</p>
  </blockquote>
  
  <p>What's perplexing is that my <code>vendor/plugins</code> directory is empty -- is there another plugins directory that it's referencing?</p>