title: shutil.rmtree doesn't work with Windows Library
body: <p>So I'm building a simple script that backs up certain documents to my second hard-drive (you never know what could happen!). So, I used the <code>shutil.copytree</code> function to replicate my data on the second drive. It works beautifully, and that is not the problem.</p>
  
  <p>I use the <code>shutil.rmtree</code> function to remove the tree if the destination already exists. I'll show you my code:</p>
  
  <pre><code>import shutil
  import os
  
  def overwrite(src, dest):
      if(not os.path.exists(src)):
          print(src, "does not exist, so nothing may be copied.")
          return
  
      if(os.path.exists(dest)):
          shutil.rmtree(dest)
  
      shutil.copytree(src, dest)
      print(dest, "overwritten with data from", src)
      print("")
  
  overwrite(r"C:\Users\Centurion\Dropbox\Documents", r"D:\Backup\Dropbox Documents")
  overwrite(r"C:\Users\Centurion\Pictures", r"D:\Backup\All Pictures")
  
  print("Press ENTER to continue...")
  input()
  </code></pre>
  
  <p>As you can see, a simple script. Now, when I run the script for the first time, everything is fine. Pictures and Documents copy over to my <code>D:</code> drive just fine. However, when I run for the second time, this is my output:</p>
  
  <pre><code>C:\Users\Centurion\Programming\Python&gt;python cpdocsnpics.py
  D:\Backup\Dropbox Documents overwritten with data from C:\Users\Centurion\Dropbox\Documents
  
  Traceback (most recent call last):
    File "cpdocsnpics.py", line 17, in &lt;module&gt;
      overwrite(r"C:\Users\Centurion\Pictures", r"D:\Backup\All Pictures")
    File "cpdocsnpics.py", line 10, in overwrite
      shutil.rmtree(dest)
    File "C:\Python34\lib\shutil.py", line 477, in rmtree
      return _rmtree_unsafe(path, onerror)
    File "C:\Python34\lib\shutil.py", line 376, in _rmtree_unsafe
      onerror(os.rmdir, path, sys.exc_info())
    File "C:\Python34\lib\shutil.py", line 374, in _rmtree_unsafe
      os.rmdir(path)
  PermissionError: [WinError 5] Access is denied: 'D:\\Backup\\All Pictures'
  </code></pre>
  
  <p>The error only happens when I copy <code>Pictures</code> after the first time; I'm assuming it has something to do with being a Library.</p>
  
  <p>What should I do?</p>