PT-2410 - pt-archiver brokes when using output-format=csv and has null values

- Added test case

t/pt-archiver/pt-2410.t

@@ -0,0 +1,75 @@
+#!/usr/bin/env perl
+
+BEGIN {
+   die "The PERCONA_TOOLKIT_BRANCH environment variable is not set.\n"
+      unless $ENV{PERCONA_TOOLKIT_BRANCH} && -d $ENV{PERCONA_TOOLKIT_BRANCH};
+   unshift @INC, "$ENV{PERCONA_TOOLKIT_BRANCH}/lib";
+};
+
+use strict;
+use warnings FATAL => 'all';
+use English qw(-no_match_vars);
+use Test::More;
+
+use charnames ':full';
+
+use PerconaTest;
+use Sandbox;
+require "$trunk/bin/pt-archiver";
+
+my $dp  = new DSNParser(opts=>$dsn_opts);
+my $sb  = new Sandbox(basedir => '/tmp', DSNParser => $dp);
+my $dbh = $sb->get_dbh_for('source');
+
+if ( !$dbh ) {
+   plan skip_all => 'Cannot connect to sandbox source';
+}
+
+my $output;
+my $exit_status;
+my $cnf = "/tmp/12345/my.sandbox.cnf";
+my $cmd = "$trunk/bin/pt-archiver";
+
+$sb->wipe_clean($dbh);
+$sb->create_dbs($dbh, ['test']);
+
+$sb->load_file('source', 't/pt-archiver/samples/pt-2410.sql');
+
+($output, $exit_status) = full_output(
+   sub { pt_archiver::main(
+      qw(--where 1=1 --output-format=csv),
+      '--source', "L=1,D=pt_2410,t=test,F=$cnf",
+      '--file',   '/tmp/pt-2410.csv') },
+);
+
+is(
+   $exit_status,
+   0,
+   'pt-archiver comleted'
+);
+
+$output = `cat /tmp/pt-2410.csv`;
+like(
+   $output,
+   qr/1,\\N,"testing..."/,
+   'NULL values stored correctly'
+) or diag($output);
+
+$dbh->do("load data local infile '/tmp/pt-2410.csv' into table pt_2410.test COLUMNS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '\"'");
+
+$output = `/tmp/12345/use pt_2410 -N -e 'SELECT * FROM test'`;
+
+like(
+   $output,
+   qr/1	NULL	testing.../,
+   'NULL values loaded correctly'
+) or diag($output);
+
+# #############################################################################
+# Done.
+# #############################################################################
+diag(`rm -f /tmp/pt-2410.csv`);
+$sb->wipe_clean($dbh);
+ok($sb->ok(), "Sandbox servers") or BAIL_OUT(__FILE__ . " broke the sandbox");
+done_testing;
+exit;

t/pt-archiver/samples/pt-2410.sql

@@ -0,0 +1,10 @@
+CREATE DATABASE pt_2410;
+USE pt_2410;
+
+CREATE TABLE test(
+    id int not null primary key auto_increment,
+    column1 int default null,
+    column2 varchar(50) not null);
+
+INSERT INTO test VALUES (null,null,'testing...');
+INSERT INTO test VALUES (null,null,'testing...');