For at least a year MacAdmins have been dealing with Apple security updates failing if they are not installed soon after being downloaded. This is especially apparent to Munki admins who have Managed Software Center (MSC) configured to install Apple updates. Munki will invoke softwareupdate to download updates as soon as they are detected but users can defer the installation via MSC indefinitely by default.
If enough time has passed when the user finally decides to allow the logout / reboot for the update it will silently fail. The computer will reboot and the user will find themselves at the login window thinking the update completed successfully. However an hour or so later softwareupdate will again detect the update, download it and MSC will prompt the user to logout and install the same update they think they had just installed.
This is not a great user experience and has led to some frustration here at the newspaper. I’ve written a script that works around this behavior, read on if you are interested in the details.