The item number in the finalize callback is off by one. This is a number for human consumption, shouldn't be 0-relative.
Build 1999-10-25-09-M11(WIN), 1999-10-25-08-M11(MAC), 1999-10-25-08-M11(LINUX) We're looking good now. Starting from [1/1] instead of [0/1].
Bulk move of XPInstall (component to be deleted) bugs to Installer: XPInstall Engine