Write todo.t

[duffee]

from https://old.reddit.com/r/perl/comments/1mbdp7b/find_accidentally_fixed_bugs_by_adding_a_test_to/

add t/run/todo.t to capture open issues

TODO: {
    $::TODO = 'GH 12345';

    my $program = '...';
    my $options = {};  # maybe `stderr => 'devnull'`?
    my $result = fresh_perl( $program, $options );
    # look at $result, which is the output of your program
    ok($?, 0, 'No assertion failure');
}

each test should reference an Issue number