Workaround: run"zman sudu <GUID>" , to delete the old system update.
The system updates that still reside in the content-repo can be found here:
The files for the system update will reside in a folder that matches the GUID of the system update.
This folder name can be used as the GUID in the ZMAN command to delete the system update.
When this command is run, the system update will be removed from the content-repo on all servers.