title: "Invalid character in filename: __static__" when deploying to Google Appengine
body: <p>I get the same issue reported <a href="https://stackoverflow.com/questions/16822630/php-app-update-invalid-character-in-filename">here</a> with my Python app. Using appengine 1.8.1, when I try to deploy, I get the following error:</p>
  
  <pre><code>Error 400: --- begin server output ---
  Invalid character in filename: __static__\static/config/sboxwsdl.xml
  </code></pre>
  
  <p>I guess it's complaining about the backslash. The part of the path "<code>__static__\</code>" is not something I can change in the application; it's done in the appengine code. Replacing os.path.join with posixpath.join in google/appengine/appcfg.py does not fix it. Here's my app.yaml file:</p>
  
  <pre><code>application: theappiamwriting
  version: 1
  runtime: python27
  api_version: 1
  threadsafe: true
  
  handlers:
  
  - url: /files/csv
    static_dir: static/csv
    mime_type: text/csv
    application_readable: true
  
  - url: /files/config
    static_dir: static/config
    mime_type: text/xml
    application_readable: true
  </code></pre>