Membership notifications with UpdateMembershipRecord.php and reminder_date of 0000-00-00

I'm using Drupal 5.x, and the latest stable CiviCRM release for that is 2.0.7, which isn't listed in the bug tracker "affects versions" pulldown. However, I've confirmed that the same problem exists in the latest 2.2.7 version.

My clients database has several membership records with a reminder date of 0000-00-00. I really don't know how these got created, you probably do; all I know is that they exist. When the UpdateMembershipRecord.php ran, it found these records and sent expiration notices. I don't know if these were inserted accidentally or intentionally, but I'd think that they should be NULL, and if not NULL, treated as NULL by UpdateMembershipRecord.php. Patch attached.