Why I want to add configure option to ignore locale is:


1. C.UTF-8 is not supported by RHEL7 (https://bugzilla.redhat.com/show_bug.cgi?id=1361965)

RHEL7 will be used for a long time.
And many people uses new Python instead of distro's Python, via pyenv or pythonz.
I feel deprecating C locale from Python 3.7 is bit aggressive.


2. Many admins like C locale.

locale setting will cause unintended side effects. So many admins dislike xx_XX.UTF-8 locale.
For example (from https://fumiyas.github.io/2016/12/25/dislike.sh-advent-calendar.html ):

$ mkdir tmp
$ cd tmp
$ touch a b c x y z A B C X Y Z
$ LC_ALL=C /bin/bash --noprofile --norc -c 'echo [A-Z]'
A B C X Y Z
$ LC_ALL=en_US.UTF-8 /bin/bash --noprofile --norc -c 'echo [A-Z]'
A b B c C x X y Y z Z


3. Many other languages can use UTF-8 even when C locale

node.js, Ruby, Rust, Go can use UTF-8 on Linux
People don't want to learn how to configure locale properly only for Python.