title: Rspec command returns '`require': cannot load such file -- spec_helper' when rake spec does not
body: <p>I am humming along running my unit tests. For each file, I write a test and then run rspec on it to make sure I've written things correctly. I'm using rvm, sourcing ruby v2.1.1. I successfully run the command <code>ruby -S spec/controllers/current_spec.rb</code> 
  At some point, I run <code>rake spec</code> for all tests
  After this, when I run <code>ruby -S spec/controllers/current_spec.rb</code> again I get the following error:</p>
  
  <pre><code>ruby -S spec/controllers/current_spec.rb 
     /home/eggmatters/.rvm/rubies/ruby-2.1.1/lib/ruby/2.1.0/rubygems/core_ext
     /kernel_require.rb:55:in `require': cannot load such file -- spec_helper (LoadError)
  from /home/eggmatters/.rvm/rubies/ruby-2.1.1/lib/ruby/2.1.0/rubygems/core_ext
     /kernel_require.rb:55:in `require'
  from spec/controllers/current_spec.rb:1:in `&lt;main&gt;'
  </code></pre>
  
  <p>The top of my spec contains:</p>
  
  <pre><code>require 'spec_helper'
  </code></pre>
  
  <p>Which is throwing the error. spec_helper is where it is supposed to be: <code>spec/spec_helper.rb</code></p>
  
  <p>Also, when running rake spec, all it does is issue the spec commands for each individual file in the spec directory for example:</p>
  
  <pre><code>$ rake spec:controllers
  /home/eggmatters/.rvm/rubies/ruby-2.1.1/bin/ruby -S rspec 
    ./spec/controllers/some_controller_spec.rb 
    ./spec/controllers/another_controller_spec.rb 
    ./spec/controllers/this_controller_spec.rb 
    ./spec/controllers/current_controller_spec.rb 
  </code></pre>
  
  <p>I've verified that <code>ruby -S</code> does indeed point to <code>/home/eggmatters/.rvm/rubies/ruby-2.1.1/bin/ruby -S</code> (<code>which ruby</code>). </p>
  
  <p>The Gemfile looks fine. Running <code>bundle exec ruby -S ./spec/controllers/current_controller_spec.rb</code> throws the same error.</p>
  
  <p>I ran rails <code>generate spec:install</code> already as I started out issuing the command just fine. There were no changes to spec_helper between successful runs.</p>
  
  <p>bundle install doesn't change anything.</p>
  
  <p>What's going on? Why is rspec <em>all of the sudden</em> not finding spec_helper when it is where it needs to be? What did rake do to rspec to all of the sudden break it? Why does rake spec work and this one doesn't? </p>