preMergeRunsWithTwoOrMoreCompacting

runs in which two or more replicas each compacted alone before the merge. One is not enough: the pre-merge phase exists to vary the merge of already-compacted states, and with a single compacted operand there is nothing to merge it with. This is the count that pins MovableTree.compactedDots, which the post-merge phase cannot see at all (see LatticeLawHarness.run).