title: Bower install packages EPERM rename error
body: <p>clean windows 7 professional installation with node and git.</p>
  
  <p>simple bower.json</p>
  
  <pre><code>{
    "name": "name123456",
    "version": "1.0.0",
    "dependencies": {
      "closure-compiler": "http://dl.google.com/closure-compiler/compiler-latest.zip"
    }
  }
  </code></pre>
  
  <p>run bower install and it dies with permission error. </p>
  
  <p><img src="https://i.stack.imgur.com/vvaWp.png" alt="error"></p>
  
  <p>any idea why this happens? thank u.</p>