add test for reported debian segfault for double free

t/bug/rt-49404-double_free.t

@@ -0,0 +1,27 @@
+#!perl -T
+
+use strict;
+use warnings;
+
+use Test::More tests => 4;
+
+use YAML::Syck;
+
+my $entry = { a => 'b' };
+my $db = [$entry, $entry];
+
+my $dump = Dump ( $db );
+is($dump, qq{--- \n- &1 \n  a: b\n- *1\n});
+
+my $dbcopy = Load ( $dump );
+is_deeply($dbcopy, $db);
+
+$dbcopy->[1] = $dbcopy->[0];
+my $dumpcopy = Dump ( $dbcopy );
+is($dump, qq{--- \n- &1 \n  a: b\n- *1\n});
+
+my $dbcopycopy = Load ( $dumpcopy );
+is_deeply($dbcopy, $db);
+
+
+