0.7.24 fixes behaviour under Python 3 (Jeroen Demeyer)

https://github.com/pynac/pynac/releases/download/pynac-0.7.24/pynac-0.7.24.tar.bz2

CC: @jdemeyer

Component: packages: standard

Author: Ralf Stephan

Branch: a6ceab9

Reviewer: Marc Mezzarobba

Issue created by migration from https://trac.sagemath.org/ticket/27241