python包管理：pip search "xxx" 为什么没有返回

 pip search --index=http://pypi.douban.com/simple mysql-python

报错

 Exception:
Traceback (most recent call last):
  File "/home/www/test/duian/venv/lib/python2.6/site-packages/pip/basecommand.py", line 134, in main
    status = self.run(options, args)
  File "/home/www/test/duian/venv/lib/python2.6/site-packages/pip/commands/search.py", line 38, in run
    pypi_hits = self.search(query, index_url)
  File "/home/www/test/duian/venv/lib/python2.6/site-packages/pip/commands/search.py", line 52, in search
    hits = pypi.search({'name': query, 'summary': query}, 'or')
  File "/usr/lib64/python2.6/xmlrpclib.py", line 1199, in __call__
    return self.__send(self.__name, args)
  File "/usr/lib64/python2.6/xmlrpclib.py", line 1489, in __request
    verbose=self.__verbose
  File "/usr/lib64/python2.6/xmlrpclib.py", line 1243, in request
    headers
ProtocolError: <ProtocolError for pypi.douban.com/simple: 301 Moved Permanently>