[3.7] bpo-28604: Fix localeconv() for different LC_MONETARY (GH-10606) by vstinner · Pull Request #10619 · python/cpython

…10619) (GH-10621)

locale.localeconv() now sets temporarily the LC_CTYPE locale to the
LC_MONETARY locale if the two locales are different and monetary
strings are non-ASCII. This temporary change affects other threads.

Changes:

* locale.localeconv() can now set LC_CTYPE to LC_MONETARY to decode
  monetary fields.
* Add LocaleInfo.grouping_buffer: copy localeconv() grouping string
  since it can be replaced anytime if a different thread calls
  localeconv().

(cherry picked from commit 02e6bf7)
(cherry picked from commit 6eff6b8)