出错信息：
Complete output from command python setup.py egg_info:
Couldn't find index page for 'incremental' (maybe misspelled?)
No local packages or download links found for incremental>=16.10.1
Traceback (most recent call last):
File"", line 1, in
File"/tmp/pip-build-wIgIGQ/Twisted/setup.py", line 21, in
setuptools.setup(**_setup["getSetupArgs"]())
File"/usr/lib/python2.7/distutils/core.py", line 111, in setup
_setup_distribution = dist = klass(attrs)
File"build/bdist.linux-x86_64/egg/setuptools/dist.py", line 260, in __init__
File"build/bdist.linux-x86_64/egg/setuptools/dist.py", line 284, in fetch_build_eggs
File"build/bdist.linux-x86_64/egg/pkg_resources.py", line 563, in resolve
File"build/bdist.linux-x86_64/egg/pkg_resources.py", line 799, in best_match
File"build/bdist.linux-x86_64/egg/pkg_resources.py", line 811, in obtain
File"build/bdist.linux-x86_64/egg/setuptools/dist.py", line 327, in fetch_build_egg
File"build/bdist.linux-x86_64/egg/setuptools/command/easy_install.py", line 434, in easy_install
File"build/bdist.linux-x86_64/egg/setuptools/package_index.py", line 475, in fetch_distribution
AttributeError: 'NoneType' object has no attribute 'clone'
Command"python setup.py egg_info" failed with error code 1 in /tmp/pip-build-wIgIGQ/Twisted/
最后解决办法：
sudo -H pip install --upgrade setuptools 或
sudo -H pip install -U setuptools
再：
sudo -H pip install scrapy
尝试过的解决办法：
1、sudo -H pip install incremental==16.10.1
2、pip install --upgrade pip
3、换豆瓣原 sudo -H pip install scrapy -i https://pypi.douban.com/simple/
