ready.Add(1)
			var count int64
			var churn func(i int)
			churn = func(i int) {
				SetGoroutineLabels(WithLabels(ctx, Labels("churn-i", fmt.Sprint(i))))
				atomic.AddInt64(&count, 1)
				if i == 0 {
					ready.Done()
				}
				if ctx.Err() == nil {
					go churn(i + 1)
				}
			}
			go func() {
				churn(0)
			}()
			ready.Wait()

			fn(b)

	)
	for _, root := range rs.rootModules {
		// If the selected version of the root is the same as what was already
		// listed in the go.mod file, retain it as a root (even if redundant) to
		// avoid unnecessary churn. (See https://golang.org/issue/34822.)
		//
		// We do this even for indirect requirements, since we don't know why they
		// were added and they could become direct at any time.

			// However, we didn't do so before Go 1.21, and the bug is relatively
			// minor, so we maintain the previous (buggy) behavior in 'go mod tidy' to
			// avoid introducing unnecessary churn.
			if keepPkgGoModSums {
				r := resolveReplacement(pkg.mod)
				keep[modkey(r)] = true
			}

			if rs.pruning == pruned && pkg.mod.Path != "" {

		//
		// We don't actually rely on that invariant at the moment, but it may
		// improve efficiency somewhat and makes the behavior a bit easier to reason
		// about (by reducing churn on the flag bits of dependencies), and costs
		// essentially nothing (these atomic flag ops are essentially free compared
		// to scanning source code for imports).
		ld.applyPkgFlags(ctx, pkg, pkgInAll)
	}