Template::Like filehandle input does not populate scalar-reference output

[fglock]

Summary

Template::Like 0.12 fails its filehandle-input test under both PerlOnJava backends. The same suite passes completely under system Perl.

Reproduction

use strict;
use warnings;
use Test::More tests => 1;
use Template::Like;

my $path = "template-like-repro-$$.tmpl";
END { unlink $path }

open my $write_fh, ">", $path or die "create $path: $!";
print {$write_fh} "[% group %]\\n";
close $write_fh;

open my $input_fh, "<", $path or die "open $path: $!";
my $template = Template::Like->new;
my $output;
$template->process($input_fh, { group => "hoge foo bar" }, \\$output)
    or die "process failed";
close $input_fh;

is($output, "hoge foo bar\\n", "filehandle input writes to scalar output");

Results

• System Perl: passes all 119 tests in the distribution.
• PerlOnJava JVM backend: the reproducer fails; the output scalar is empty/undefined.
• PerlOnJava interpreter backend: same failure.
• Other Template::Like input forms in the distribution test pass.

The archived CPAN run 20260902-105746-25731 recorded this as a regression: the previous pass was on 2026-08-18 at commit e9739bcbf. The original failing test is t/input.t, test 3 (filehandle).

Likely area for investigation: shared filehandle input and scalar-reference output handling in Template::Like->process().