Bootstrap doesn't work when the python-pkg-resources is installed in Debian systems

I'm trying to bootstrap a buildout on a newly installed Ubuntu Lucid Lynx system, and the bootstrap fails with:

# python2.4 bootstrap.py
Traceback (most recent call last):
  File "bootstrap.py", line 112, in ?
    PYTHONPATH=
AttributeError: 'NoneType' object has no attribute 'location'

The line where it fails is:

    assert os.spawnle(
        os.P_WAIT, sys.executable, quote (sys.executable),
        '-c', quote (cmd), '-mqNxd', quote (tmpeggs), 'zc.buildout' + VERSION,
        dict(os.environ,
            PYTHONPATH=
            ws.find(pkg_resources.Requirement.parse(requirement)).location
            ),
        ) == 0

I was able to solve the problem by removing the python-pkg-resources package. I think the bootstrap script, being able to import pkg_resources, assumes that I have Distribute or Setuptools installed, which is not the case.