If Py3K is executed without importing site, it fails horribly.  This is
because site.py sets __builtins__.open, sys.stdout, sys.stderr, and
sys.stdin.

The setting of sys.stderr is especially bad as exception printing
requires sys.stderr, otherwise it reports that sys.stderr was lost. 
This prevents debugging any exceptions thrown when site.py isn't/can't
be imported (e.g., trying to debug bootstrapping importlib).