Postpone UTF-8 default external encoding to Ruby-2.6 [ci skip]
Postpone UTF-8 default external encoding to Ruby-2.6 [ci skip]

... because readline still doesn't work on Windows and I didn't had
the time to fix it or work on https://github.com/larskanis/rb-readline
towards better encoding and character support.
larskanis/rubyinstaller2,oneclick/rubyinstaller2,larskanis/rubyinstaller2,larskanis/rubyinstaller2,oneclick/rubyinstaller2,oneclick/rubyinstaller2