bpo-32837: IDLE - require encoding argument for textview.view_file. (GH-5646)


Using the system and place-dependent default encoding for open()
is a bad idea for IDLE's system and location-independent files.
(cherry picked from commit 688722cedd6437910ff185ecf94fb3b749ad37f2)

Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>
3 files changed