Message 175754 - Python tracker

The issue is not only in difference between Python and C implementations, but also between 32-bit and 64-bit.

pickle.py on 32-bit accepts data up to 2G.
pickle.py on 64-bit accepts data up to 2G.
_pickle.c on 32-bit accepts data up to 2G.
_pickle.c on 64-bit accepts data up to 4G.

3:1 for 2G.  Current _pickle.c behavior is just not portable.

Of course, I can rewrite the patch, expanding the limit to 4G on 64-bit if you insist.  But I doubt that this is the best variant.