Fakeclient patch: if new object has no rv and oldObjs rv matches whats in the tracker, we allow unconditional update

[alvaroaleman]

Fallout from #2976: The patch should be calculated by between the passed object and the object in the patch. The fakeclient however calculates it between the latest version in the tracker and the object in the patch. This means that if the RV in the passed object and the object in the patch differ but the latter matches whats in the tracker, the fake client allows the patch to go through when it shouldn't.

[alvaroaleman]

Actually this is correct behavior (but confusing): If a patch ends up containing a RV but the RV is current, the KAS will apply it.