根据http://treq.readthedocs.org/en/latest/，可以使用 pip 安装treq，但是它失败了。我可以使用 tar 文件安装 treq，但我想知道为什么这会失败，因为http://pypi.python.org/simple/treq/有 0.1.0 和 0.2.0。
$ sudo pip install treq
Downloading/unpacking treq
Cannot fetch index base URL http://pypi.python.org/simple/
Could not find any downloads that satisfy the requirement treq
No distributions at all found for treq
Storing complete log in <cut>.pip/pip.log
$ pip search treq
megrok.strictrequire - Checks that all grokked "view-like" components
require a permission.
streql - Constant-time string comparison
trequests - A Tornado async HTTP/HTTPS client adaptor for
python-requests
treq - A requests-like API built on top of twisted.web's
Agent
repoze.bfg.restrequest - a REST aware Request for implementing RESTful
applications with repoze.bfg
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刚尝试从 tarfile 安装，也找不到扭曲的，所以想知道 pip 是否存在基本问题...
$ sudo python setup.py install
running install
Checking .pth file support in /usr/local/lib/python2.7/dist-packages/
<snip>
Extracting treq-0.2.0-py2.7.egg to /usr/local/lib/python2.7/dist-packages
Adding treq 0.2.0 to easy-install.pth file
Installed /usr/local/lib/python2.7/dist-packages/treq-0.2.0-py2.7.egg
Processing dependencies for treq==0.2.0
Searching for Twisted>=12.1.0
Reading http://pypi.python.org/simple/Twisted/
Download error on http://pypi.python.org/simple/Twisted/: timed out -- Some packages may not be found!
Reading http://pypi.python.org/simple/Twisted/
Download error on http://pypi.python.org/simple/Twisted/: timed out -- Some packages may not be found!
Couldn't find index page for 'Twisted' (maybe misspelled?)
Scanning index of all packages (this may take a while)
Reading http://pypi.python.org/simple/
Download error on http://pypi.python.org/simple/: timed out -- Some packages may not be found!
No local packages or download links found for Twisted>=12.1.0
error: Could not find suitable distribution for Requirement.parse('Twisted>=12.1.0')
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