pi@cohoserver /usr/lib/python2.7/dist-packages $ sudo pip install --upgrade numpy
**Cannot fetch index base URL https://pypi.python.org/simple/**
Could not find any downloads that satisfy the requirement numpy in /usr/lib/pymodules/python2.7
Downloading/unpacking numpy
Cleaning up...
No distributions at all found for numpy in /usr/lib/pymodules/python2.7
Storing debug log for failure in /root/.pip/pip.log
pi@cohoserver ~ $ sudo git clone https://github.com/ziahamza/webui-aria2.git
Cloning into 'webui-aria2'...
**error: server certificate verification failed. CAfile: /etc/ssl/certs/ca-certificates.crt CRLfile: none while accessing https://github.com/ziahamza/webui-aria2.git/info/refs
fatal: HTTP request failed**
終於解決問題了，原來是樹莓派的時間設定問題，現在一切都完美了。
所有的SSL問題都搞定。
我這裡目前沒辦法訪問 https://pypi.python.org/simple 即使翻牆。建議改用 douban(http://pypi.douban.com/simple) 或 v2ex(http://pypi.v2ex.com/simple) 的來源。將下面內容加到 ~/.pip/pip.conf 中