[3.6] bpo-30584: Fix test_os fails on non-English Windows (GH-1980) (#1999)

* Fix bpo-30584

* Adding a comment mentionning the bpo and explaining what is the identifier

* Add Denis Osipov to Misc/ACKS
(cherry picked from commit 897bba75632dfce87c355e3cd4700468357715a7)
2 files changed