Wait, should Doc/tools/sphinxext be included in the source tarball or
not?  I thought it was a documentation build artifact.  If so, then we
need to clean out the pycs it contains in a different way.

In any case, the 3.0 tarballs should include sphinxext for better or
worse, because this directory is removed by the release.py script. 
However, the removal of it was not added to release.py until after the
3.0 tarballs were made (the 2.6.1 tarballs do not include sphinxext).

Tell me which it should be and I'll fix release.py