pyspider框架的599证书问题

HTTP 599: SSL certificate problem: unable to get local issuer certificate 
[E 161018 21:56:36 base_handler:195] HTTP 599: SSL certificate problem: unable to get local issuer certificate 
Traceback (most recent call last): 
File “C:\Python27\lib\site-packages\pyspider\libs\base_handler.py”, line 188, in run_task 
result = self._run_task(task, response) 
File “C:\Python27\lib\site-packages\pyspider\libs\base_handler.py”, line 167, in _run_task 
response.raise_for_status() 
File “C:\Python27\lib\site-packages\pyspider\libs\response.py”, line 190, in raise_for_status 
raise http_error 
HTTPError: HTTP 599: SSL certificate problem: unable to get local issuer certificate