python requests 报错： Cannot connect to proxy

昨晚写一个的小程序，用到requests-future库。本来好好的，今天突然报这样的错误：

`Traceback (most recent call last):
File "/usr/lib/python3/dist-packages/requests/adapters.py", line 330, in send
timeout=timeout
File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 599, in urlopen
'Socket error: %s.' % e)
urllib3.exceptions.ProxyError: Cannot connect to proxy. Socket error: [Errno 111] Connection refused.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/lib/python3/dist-packages/requests/sessions.py", line 467, in get
return self.request('GET', url, **kwargs)
File "/usr/lib/python3/dist-packages/requests/sessions.py", line 455, in request
resp = self.send(prep, **send_kwargs)
File "/usr/lib/python3/dist-packages/requests/sessions.py", line 558, in send
r = adapter.send(request, **kwargs)
File "/usr/lib/python3/dist-packages/requests/adapters.py", line 381, in send
raise ProxyError(e)
requests.exceptions.ProxyError: Cannot connect to proxy. Socket error: [Errno 111] Connection refused.`

代码则很简单：
`

from requests import Session
s = Session()
one = s.get('http://www.baidu.com/')
`

我不知道为什么突然会这样子报错，怀疑是不是我安装shadowsock后设置了全局代理，但我已经关闭了代理，也没有启动ss，在系统设置也设置了代理为无。

目前使用的系统: elementary os