Patch to remove call to /usr/bin/sw_vers on OSX
This is a copy of http://bugs.python.org/setuptools/issue70:
The attached patch for setuptools 0.6c9 replaces a shell callout to /usr/bin/sw_vers to using platform.mac_ver on OSX.
The primary reason for writing the patch is that gdb tends to cause havoc with calls to os.popen (the debugged process gets an signal and debugging gets aborted).
This patch makes it a lot more convenient to run "setup.py test" in a gdb session, without this patch I regularly have to re-run the tests several times until the callout to sw_vers succeeds.