ordereddict not installed with pip 1.1

[radekholy24]

Reproducer:

1. run a system with pip 1.1 (in my case, a Vagrant box based on debian/wheezy64)
2. create a Python 2.6 virtual environment (virtualenv --python=python2.6 venv)
3. activate the environment (source venv/bin/activate)
4. follow the funcsigs's installation instructions (I did not find any, thus pip install funcsigs)
5. import funcsigs (python -c "import funcsigs")

Actual behavior:

An ImportError with the following traceback:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/home/vagrant/venv/lib/python2.6/site-packages/funcsigs/__init__.py", line 16, in <module>
    from ordereddict import OrderedDict
ImportError: No module named ordereddict

Expected behavior:

funcsigs can be imported

Affected versions:

• funcsigs 1.0.2
• pip 1.1
• Python 2.6

Additional information

If I upgrade pip (to 8.1.2), everything seems to work. Thus I guess that funcsigs has to express the dependency on a newer pip. I am not sure whether it might be achieved by setup_requires like you did before. If not, at least a note in installation instructions (which has to be propagated to mock and others) would be nice.
Please note that upgrading setuptools (to 28.6.0) (even before issuing the installation of funcsigs) was not enough in my case.