title: When attempting run a python script from within another python script, I get 'permission denied'!
body: <p>So, I was writing a python script, and it automatically downloads an update at the beginning of the script. Ok, so? So when I try to overwrite it, it gives me <code>sh: /Users/&lt;user&gt;/Desktop/&lt;scriptname&gt;.py: Permission denied</code> using CodeRunner 2.0.2, IDLE 2.7.9, and PythonLauncher. Here's the affected snippit:</p>
  
  <pre><code>cwd = os.getcwd()
  cwd = (str(cwd) + "/&lt;scriptname&gt;.py")
  update = urllib.URLopener()
  cwd = str(cwd)
  print "Downloading Update..."
  update.retrieve("http://&lt;site_domain&gt;/&lt;scriptname&gt;.py",cwd)
  time.sleep(1.25)
  print "Update Dowloaded! Please Wait..."
  time.sleep(2.5)
  os.system(cwd)
  </code></pre>
  
  <p>I found this odd since people say that it should overwrite no problemo, however, I found it odd when there was no brother <code>.pyc</code>, meaning it may have been attempting to read and write at the same time, not to mention it worked fine, then suddenly went kaput.</p>