TL;DR - Just one more example of why nobody should *ever* use pickle under any circumstances.  It is useless for data that is not transient for consumption by the same exact versions of all software that created it.

Patches against 2.7 are not useful here.  Either we write a unpickle deserializer for python 2 datetime pickles that works for all existing previous datatime pickled data formats from Python 3.  Or we close this as rejected because the data formats are rightly incompatible as the in-process object states are incompatible between the two versions.

If you want to serialize something, use a language agnostic data format - ideally one with a defined schema.  Never pickle.

Advice for those who have stored such data in Python 2 pickles: Write a Python 2 program to read your data and rewrite it in a portable data format that has nothing to do with pickle.  Anything else is a gross hack.