STDERR PerlIO layers are not preserved

[kamholz]

Setting binmode STDERR, ':encoding(UTF-8)' is not always preserved when using Capture::Tiny. The docs say it tries to do this, but evidently it doesn't succeed. The following test case demonstrates the error on version 0.44, Perl 5.24.0:

use strict;
use warnings;
use utf8;
use Capture::Tiny qw(capture capture_stdout);
use Data::Dumper;
binmode STDOUT, ':encoding(UTF-8)';
binmode STDERR, ':encoding(UTF-8)';

my $output = capture_stdout { print "eng-rus-Тверитнев\neng-rus-Тверитнев\neng-rus-Тверитнев" };

foreach my $file (split /\n/, $output) {
    print Dumper([ 1, PerlIO::get_layers(STDERR) ]);
    print STDERR $file, "\n";
    print Dumper([ 2, PerlIO::get_layers(STDERR) ]);
    my ($foo) = capture { print $file };
    print Dumper([ 3, PerlIO::get_layers(STDERR) ]);
}

The resulting output shows several "Wide character in print" warnings, and that the PerlIO layers are reset:

$VAR1 = [
          1,
          'unix',
          'perlio',
          'encoding(utf-8-strict)',
          'utf8'
        ];
Wide character in print at test.pl line 13.
eng-rus-Тверитнев
$VAR1 = [
          2,
          'unix',
          'perlio',
          'encoding(utf-8-strict)',
          'utf8'
        ];
$VAR1 = [
          3,
          'unix',
          'perlio'
        ];
$VAR1 = [
          1,
          'unix',
          'perlio'
        ];
Wide character in print at test.pl line 13.
eng-rus-Тверитнев
$VAR1 = [
          2,
          'unix',
          'perlio'
        ];
$VAR1 = [
          3,
          'unix',
          'perlio'
        ];
$VAR1 = [
          1,
          'unix',
          'perlio'
        ];
Wide character in print at test.pl line 13.
eng-rus-Тверитнев
$VAR1 = [
          2,
          'unix',
          'perlio'
        ];
$VAR1 = [
          3,
          'unix',
          'perlio'
        ];