Codepages seem to be the sticky wicket:
C:\Users\tblaz\Documents\evelyn>perl 1.hello.cyr.pl
default encoding:
Active code page: 437
Привет
------------
Active code page: 65001
Привет
#!/usr/bin/perl -w
use 5.016;
use utf8::all;
#binmode STDOUT, ":utf8";
say "default encoding:";
system "chcp";
say "Привет";
say "------------";
system "chcp 65001";
say "Привет";
__END__
Once the right codepage is present, the test succeeeds:
C:\Users\tblaz\Documents\evelyn>perl 1.cyr.pl
...
-------
Content-Type: text/html; charset=utf-8
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Мой тест</title>
</head>
<body>
Бабкинъ Михаилъ
</body>
</html>
C:\Users\tblaz\Documents\evelyn>
Now I wonder how to make that the default setting....