Can someone please try to write an example which only uses the stdlib?

> The culprit is the isdigit function called in the parsers extension module.

What are these extensions? Where do them come from?

> Any way you can help test out a config setting to avoid the locale changes on Python 3.7.0a4+?

(I fixed 2.7 => 3.7)

I don't understand which "locale changes" you are talking about. You can change the locale using locale.setlocale().