> > I’d be grateful if someone could post links to discussion
> > about the removal of codecs like hex and rot13
> r55932 (~3 years ago):

That was my commit. ;)

> Thanks for the link. Do you have a pointer to the PEP or ML thread
> discussing that change?

The removal is documented here: http://www.artima.com/weblogs/viewpost.jsp?thread=208549

"""
We are adopting a slightly different approach to codecs: while in Python 2, codecs can accept either Unicode or 8-bits as input and produce either as output, in Py3k, encoding is always a translation from a Unicode (text) string to an array of bytes, and decoding always goes the opposite direction. This means that we had to drop a few codecs that don't fit in this model, for example rot13, base64 and bz2 (those conversions are still supported, just not through the encode/decode API).
"""

A post by Georg Brandl about this is at http://mail.python.org/pipermail/python-3000/2007-June/008420.html

(Note that this thread began in private email between Guido, MvL, Georg and myself. If needed I can dig up the emails.)