"However, I'd still like to discuss the idea of backporting this to 3.4.1."

THe idea of doing this change in Python 3.5 is that I have no idea of the risk of regression. To backport such change in a minor version (3.4.1), I would feel more confident with user tests of Python 3.5 or patched Python 3.4.

"That has long made Toshio nervous about the migration of core services to Python 3 (https://fedoraproject.org/wiki/Changes/Python_3_as_Default), and his concerns make sense to me, as that migration covers little things like the installer, package manager, post-image install initialisation, etc. "

Which programs in this test are or may be running with the POSIX locale?

Fedora doesn't use en_US.utf8 locale by default?