在ubuntu 11.10中由于官方apt库自带的gevent和libevent导致gevent.wsgi模块不能正常工作。
在升级gevent到gevent-0.13.7之后，提示和libevent 的版本不兼容，应升级到libevent-2.0.16-stable以上。
升级之后，代码一切正常。
关于gevent的wsgi和pywsgi有下面的详细说明：
Gunicorn has 3 gevent workers:
- -k gevent (using gunicorn’s HTTP parser)
- -k gevent_pywsgi (using gevent.pywsgi module)
- -k gevent_wsgi (using gevent.wsgi module)
gevent.wsgi is a fast HTTP server based on libevent.
gevent.pywsgi is WSGI server implemented in Python.
The reason for existence of gevent.pywsgi is libevent-http having a few limitations, such as not supporting keep-alive, streaming, ssl and websocket