setup: use try/except/finally
This will raise a syntax error for people who attempt to use Py2.4,
but that's already going to fail and we have no way to keep other
2.6isms from creeping in since we've removed the check-code rules and
the buildbot.
Greg Ward, author of the original bfiles extension
Na'Tosha Bard of Unity Technologies
Fog Creek Software
Special thanks to the University of Toronto and the UCOSP program