Sorry about that, I should have investigated this problem further before raising
it to zooko.

To reproduce this problem independently:
 1: create Nevow-0.9.31-py2.5.egg
 2: put it in a child directory FOO
 3: run PYTHONPATH=FOO python -c 'import twisted'

I haven't yet been able to figure out how to accomplish step 1 outside of our
Tahoe build system. We do it with a "setup.py develop" that sees a dependency on
Nevow that needs satisfying. Apparently there is something broken in the Nevow
setup.py (or rather their setup_egg.py), as a regular "bdist_egg" doesn't seem
to work.