Develop broken for projects using modules in the distribution root

Projects using modules in the project distribution root in their setup.py fail when used in the buildout develop option.

This can be reproduced, for example, by using ez_setup as described in:

http://peak.telecommunity.com/DevCenter/setuptools#id23

To reproduce make an empty directory and make an empty module, bar.py in the directory:

  """Empty bar module"""

Download bootstrap.py into it:

http://peak.telecommunity.com/dist/ez_setup.pyhttp://svn.zope.org/*checkout*/zc.buildout/trunk/bootstrap/bootstrap.py

Then make a setup.py that imports foo::

    #!/usr/bin/env python
    import bar

    from setuptools import setup

    setup(name='foo')

Make an buildout.cfg that passes the project to the develop option::

    [buildout]
    develop = .

Then bootstrap buildout::

    $ python bootstrap.py -v

Finally run buildout. Note that an error occurs importing ez_setup::

    $ bin/buildout -v
    Installing 'zc.buildout', 'setuptools'.
    We have the best distribution that satisfies 'zc.buildout'.
    Picked: zc.buildout = 1.0.0b30
    We have the best distribution that satisfies 'setuptools'.
    Picked: setuptools = 0.6c7
    Develop: '/tmp/foo/.'
    Traceback (most recent call last):
      File "/tmp/tmpsDYTIA", line 10, in ?
        execfile('/tmp/foo/./setup.py')
      File "/tmp/foo/./setup.py", line 2, in ?
        import bar
    ImportError: No module named bar
    While:
      Installing.
      Processing develop directory '/tmp/foo/.'.

    An internal error occured due to a bug in either zc.buildout or in a
    recipe being used:

    AssertionError: