title: Sass --watch breaking after Yosemite update
body: <p>After updating to Yosemite on my Macbook Pro, sass --watch no longer functions. I get the following:</p>
  
  <pre><code>&gt;&gt;&gt; Sass is watching for changes. Press Ctrl-C to stop.
  Ignoring bigdecimal-1.2.5 because its extensions are not built.  Try: gem pristine bigdecimal-1.2.5
  Ignoring ffi-1.9.5 because its extensions are not built.  Try: gem pristine ffi-1.9.5
  Ignoring ffi-1.9.3 because its extensions are not built.  Try: gem pristine ffi-1.9.3
  Ignoring json-1.8.1 because its extensions are not built.  Try: gem pristine json-1.8.1
  Ignoring libxml-ruby-2.7.0 because its extensions are not built.  Try: gem pristine libxml-ruby-2.7.0
  Ignoring nokogiri-1.6.3.1 because its extensions are not built.  Try: gem pristine nokogiri-1.6.3.1
  Ignoring psych-2.0.6 because its extensions are not built.  Try: gem pristine psych-2.0.6
  </code></pre>
  
  <p>"gem pristine" doesn't do anything. I tried on Sass 3.4.5 and 3.4.6. Unsure how to resolve.</p>