AttributeError: 'NoneType' object has no attribute 'url'

[fpatwa]

Error in running devstack:
2015-04-14 21:50:54.898 | + python update.py /opt/stack/keystone
2015-04-14 21:50:55.180 | Traceback (most recent call last):
2015-04-14 21:50:55.181 | File "update.py", line 274, in
2015-04-14 21:50:55.181 | main(options, args)
2015-04-14 21:50:55.181 | File "update.py", line 259, in main
2015-04-14 21:50:55.187 | _copy_requires(options.suffix, options.softupdate, args[0])
2015-04-14 21:50:55.187 | File "update.py", line 219, in _copy_requires
2015-04-14 21:50:55.187 | source_reqs = _parse_reqs('global-requirements.txt')
2015-04-14 21:50:55.187 | File "update.py", line 140, in _parse_reqs
2015-04-14 21:50:55.187 | reqs[_parse_pip(pip)] = pip
2015-04-14 21:50:55.187 | File "update.py", line 101, in _parse_pip
2015-04-14 21:50:55.187 | elif install_require.url:
2015-04-14 21:50:55.187 | File "/usr/local/lib/python2.7/dist-packages/pip/req/req_install.py", line 128, in url
2015-04-14 21:50:55.187 | return self.link.url
2015-04-14 21:50:55.188 | AttributeError: 'NoneType' object has no attribute 'url'

Solution:
cd /opt/stack/devstack
./unstack.sh

Delete the requirements directory

rm –fr /opt/stack/requirements

Re-run stack.sh

./stack.sh