[Pythonmac-SIG] Why dynload_next.c rather than dynload_shlib.c?

[Phil Thompson]

Apple's Python seems to be built with dynload_shlib.c which allows it to 
handle extension modules built as bundles and dynamic libraries.

python.org Python uses dynload_next.c which means that extension modules must 
be built as bundles.

Is there any particular reason for this (I'm new to MacOS)?

Thanks,
Phil