title: Error `comparison of Symbol with Module failed` after upgrading to Rspec 3
body: <p>I just upgraded from Rspec 2.99 to Rspec 3 and am getting the following error for some of my tests.</p>
  
  <pre><code>Failure/Error: Unable to find matching line from backtrace
  ArgumentError:
    comparison of Symbol with Module failed
  </code></pre>
  
  <p>I have the following controller test</p>
  
  <pre><code>require 'spec_helper'
  
  describe PeopleController, type: :controller do
    subject { response }
  
    describe :index do
      before { get :index }
  
      it { should_not be_success }
      it { should have_http_status '401' }
    end
  end
  </code></pre>
  
  <p>Any idea what might be causing the error?</p>