smallest mongo+test-simple script

gistfile1.pl

use strict;
use warnings;
use Test::More 'no_plan';

use MongoDB::Timestamp; # needed if db is being run as master
use MongoDB;

use lib "t/lib";
use MongoDBTest qw/build_client get_test_db/;

my $conn = build_client();
my $testdb = get_test_db($conn);
$testdb->drop;
my $dbname = $testdb->name;
my $coll = $conn->ns("$dbname.test_collection");
$coll->ensure_index({"x.y" => 1}, {"name" => "foo"});

ok(1);
my ($index) = grep { $_->{name} eq 'foo' } $coll->get_indexes;
ok(1);


__END__  

Ways to make the problem go away:

ok(1);   
my ($index) = grep { $_->{name} eq 'foo' } $coll->get_indexes;
$index = undef
ok(1);   


ok(1);   
{
    my ($index) = grep { $_->{name} eq 'foo' } $coll->get_indexes;
}
ok(1);   


ok(1);   
grep { $_->{name} eq 'foo' } $coll->get_indexes;
ok(1);

As the MongoDB module is involved, could you post the $VERSION or the commit of MongoDB?

What about a temporary array to hold the result of $coll->get_indexes? Will that also make the problem go away?