bpo-34108: Fix double carriage return in 2to3 on Windows (GH-8271) (#8275)

* Add test capturing failure.
* Honor newlines as present in the original file.
(cherry picked from commit cafaf0447b950fd4f59edd8cbde040c61ae528f8)

Co-authored-by: Jason R. Coombs <jaraco@jaraco.com>
3 files changed