reasons for python31?

[Thomas Klausner <tk%giga.or.at@localhost>]

We have three python3 versions in pkgsrc, python31, python32 and
python33.

The last published update for python was only released for python27,
python32 and python33 -- not for python31.

Does anyone know of a particular reason why having python31 in
addition to python32 and python33 serves a purpose? Is there code that
only works in that version and is not trivially ported to either newer
version?

 Thomas