requests 抓取网页，在 python shell 运行正常，文件执行报错，求原因

python shell运行正常

import requests
r = requests.get('https://www.google.com')
r.content

存为文件python google.py运行报错

r = requests.get('https://www.google.com')
File "/usr/local/lib/python2.7/site-packages/requests/api.py", line 60, in get
return request('get', url, **kwargs)
File "/usr/local/lib/python2.7/site-packages/requests/api.py", line 49, in request
return session.request(method=method, url=url, **kwargs)
File "/usr/local/lib/python2.7/site-packages/requests/sessions.py", line 457, in request
resp = self.send(prep, **send_kwargs)
File "/usr/local/lib/python2.7/site-packages/requests/sessions.py", line 569, in send
r = adapter.send(request, **kwargs)
File "/usr/local/lib/python2.7/site-packages/requests/adapters.py", line 362, in send
timeout=timeout
File "/usr/local/lib/python2.7/site-packages/requests/packages/urllib3/connectionpool.py", line 516, in urlopen
body=body, headers=headers)
File "/usr/local/lib/python2.7/site-packages/requests/packages/urllib3/connectionpool.py", line 304, in _make_request
self._validate_conn(conn)
File "/usr/local/lib/python2.7/site-packages/requests/packages/urllib3/connectionpool.py", line 722, in _validate_conn
conn.connect()
File "/usr/local/lib/python2.7/site-packages/requests/packages/urllib3/connection.py", line 169, in connect
self.sock = ssl.wrap_socket(conn, self.key_file, self.cert_file)
AttributeError: 'NoneType' object has no attribute 'wrap_socket'