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

[vinta]

Downloading/unpacking haul
  Running setup.py egg_info for package haul
    Traceback (most recent call last):
      File "<string>", line 14, in <module>
      File "/home/vagrant/.virtualenvs/hauler/build/haul/setup.py", line 22, in <module>
        install_requires = [str(item.req) for item in parse_requirements('requirements.txt')]
      File "/home/vagrant/.virtualenvs/hauler/local/lib/python2.7/site-packages/pip-1.1-py2.7.egg/pip/req.py", line 1240, in parse_requirements
        skip_regex = options.skip_requirements_regex
    AttributeError: 'NoneType' object has no attribute 'skip_requirements_regex'
    Complete output from command python setup.py egg_info:
    Traceback (most recent call last):

  File "<string>", line 14, in <module>

  File "/home/vagrant/.virtualenvs/hauler/build/haul/setup.py", line 22, in <module>

    install_requires = [str(item.req) for item in parse_requirements('requirements.txt')]

  File "/home/vagrant/.virtualenvs/hauler/local/lib/python2.7/site-packages/pip-1.1-py2.7.egg/pip/req.py", line 1240, in parse_requirements

    skip_regex = options.skip_requirements_regex

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

error install with pip 1.1, but fine with pip 1.4.1