[3.6] bpo-31900: Fix localeconv() encoding for LC_NUMERIC (#4174) by vstinner · Pull Request #5192 · python/cpython

the-knights-who-say-ni

* Add _Py_GetLocaleconvNumeric() function: decode decimal_point and
  thousands_sep fields of localeconv() from the LC_NUMERIC encoding,
  rather than decoding from the LC_CTYPE encoding.
* Modify locale.localeconv() and "n" formatter of str.format() (for
  int, float and complex to use _Py_GetLocaleconvNumeric()
  internally.

(cherry picked from commit cb064fc)