I'm currently running Mavericks on what we'll call Drive A. Let's say I wanted to test-drive Yosemite to make sure all my software works okay. If I clone Drive A to an empty Drive B to back it up, and install Yosemite on Drive A, will iCloud do any upgrades that will make it inoperable in Mavericks? I know there's the new iCloud Drive. I basically don't want Apple's servers to see that I've upgraded to Yosemite and make it not possible to have a working iCloud under Mavericks should I decide to clone Drive B back to Drive A.