7244d6d11d
The original idea was that stacks of loose nodes should repack from the bottom up, and self-repacking should never "race" against reposing. If the node is sitting on a solid node, it can always self-repack. If it's sitting on a loose node, then only repack if the node below is not itself in the process of self-repacking, and if the node itself isn't awaiting reposing.