}
			}
			return rootPruning
		}
		for _, m := range roots {
			extendedRootPruning[m] = findPruning(m)
		}
		for m := range upgradedRoots {
			extendedRootPruning[m] = findPruning(m)
		}

		// Now check the resulting extended graph for errors and incompatibilities.
		t := dqTracker{extendedRootPruning: extendedRootPruning}
		mg.g.WalkBreadthFirst(func(m module.Version) {