> Note that on Linux, 32-bit and 64-bit versions are typically placed
> into different directory trees

By whom? Our standard installer doesn't (it uses ../lib/python-X.Y for all builds).

Also, one of the problems (and actually the problem which triggered this tracker entry) is when doing development inside a working copy (either through "setup.py develop" or "setup.py build_ext --inplace" - both copy C extensions directly into the source tree).