A peculiar anomaly. I have just installed , from the ISO, 9879, for a colleague. His computer has not been loaded with any earlier builds. After loading, and arriving at the desktop, I went quickly to the updates. None waiting at that stage. So I "checked for updates", a whole load of the monthlies came down, with the definition updates. I was able to hide, or uncheck., but I let it go ahead.
It seems to be a way, for those determined, to bypass the compulsory installation requirement.