[3.9] bpo-37751: Document codecs.lookup() change in What's New in Python 3.9 (GH-23096) by miss-islington · Pull Request #25659 · python/cpython

@@ -1114,6 +1114,12 @@ Changes in the Python API compatible classes that don't inherit from those mentioned types. (Contributed by Roger Aiudi in :issue:`34775`).
* :func:`codecs.lookup` now normalizes the encoding name the same way as :func:`encodings.normalize_encoding`, except that :func:`codecs.lookup` also converts the name to lower case. For example, ``"latex+latin1"`` encoding name is now normalized to ``"latex_latin1"``. (Contributed by Jordon Xu in :issue:`37751`.)

Changes in the C API --------------------