Good argument, and I think I'm convinced by this point; even though duplicating the .py files goes against my grain, that's probably just a sign of my age.
Oh, you gen-X'ers thinking you're old... Have you had your prostate checked lately? :-)
But what platform-specific directory should packages be installed into? Is <prefix>/plat-<sys.platform> the right place? Or do we need site-packages/plat-<sys.platform>? (Yet Another default directory added to sys.path -- yuck!)
This is supported by site.py:
""" This will append site-specific paths to to the module search path. On Unix, it starts with sys.prefix and sys.exec_prefix (if different) and appends lib/python<version>/site-packages as well as lib/site-python. On other platforms (mainly Mac and Windows), it uses just sys.prefix (and sys.exec_prefix, if different, but this is unlikely). The resulting directories, if they exist, are appended to sys.path, and also inspected for path configuration files. """
(Note that lib/site-python is obsolete!)
--Guido van Rossum (home page: http://www.python.org/%7Eguido/)