As you can see from the ldif the cn attribute is clearly present. I am assuming this is a bug and needs reported but wanted to review it with the list members before I submitted the ITS entry.
slapd is doing exactly what you asked of it. You set: deleteoldrdn: 1, so it complied and deleted the cn: value. If you want cn preserved, then I suggest you don't ask slapd to delete it on rename.
--Quanah -- Quanah Gibson-Mount Architect - Server Zimbra, Inc. -------------------- Zimbra :: the leader in open source messaging and collaboration