title: Flattening of File Tree when using Grunt Copy Task
body: <p>Not sure if I'm missing something but I have the following grunt setup for grunt-contrib-copy tasks.</p>
  
  <pre><code>copy: {
    build: {
      files: {
        "server-dist/": "server/**/*.!(coffee)",
        "client-dist/": "client/**/*.!(coffee)"
      }
    }
  }
  </code></pre>
  
  <p>The client-dist copies as I expect recursively running through the file tree but the server-dist all sub-folders get flattened to the base folder. Any ideas why this is happening? Here is the i/o</p>
  
  <pre><code>server/
    views/
      errors/
        404.jade
      layouts/
        base.jade
  </code></pre>
  
  <p>becomes</p>
  
  <pre><code>server/
    errors/
    layouts/
      base.jade
  </code></pre>
  
  <p>the views folder gets completely blown out. One more thing...when I removed !(coffee) it works but I need to exclude coffee files since I have a grunt-coffee watch task running.</p>