pip无法安装任何软件包 - ssl.py错误

Question

每当我尝试从pip（Flask，Github-Flask，Django甚至升级setuptools）安装任何软件包时，我总是遇到这个错误：

File "/usr/lib/python2.7/socket.py", line 380, in read
    data = self._sock.recv(left)
File "/usr/lib/python2.7/httplib.py", line 561, in read
    s = self.fp.read(amt)
File "/usr/lib/python2.7/socket.py", line 380, in read
    data = self._sock.recv(left)
File "/usr/lib/python2.7/ssl.py", line 241, in recv
    return self.read(buflen)
File "/usr/lib/python2.7/ssl.py", line 160, in read
    return self._sslobj.read(len)
error: [Errno 104] Connection reset by peer

我正在使用Kubuntu 12.04，python 2.7。我已经尝试重新安装python2.7和pip。有什么想法吗？