Comment 5 for bug 1500890

Or it could be the web server being used. Handling of %2F is notoriously painful. Some servers will explicitly manipulate it in PATH_INFO so that it goes back to '/' before getting to the WSGI app.

Which is _really_ annoying. Here's an example from my past: https://github.com/tiddlyweb/tiddlyweb/blob/master/tiddlyweb/web/serve.py#L119

See also: http://httpd.apache.org/docs/current/mod/core.html#allowencodedslashes (which frequently doesn't actually work).