calculatePendingRanges assigns more pending ranges than necessary

This might be a good thing, but should probably be configurable, and made consistent. Presently, in a number of circumstances where there are multiple range movements, calculatePendingRanges will assign a pending range to a node that will not ultimately own it. If done consistently, this might make range movements resilient to node failures / aborted range movements, since all nodes will be receiving all ranges they might own under any incomplete range ownership movements. But done inconsistently it seems only to reduce availability in the cluster, by potentially increasing the number of pending nodes unnecessarily.