Give a fast-renewing test lease a serving controller's time to renew, and prove the minted hash's cost

A renewal timed out at the renew interval, so the lease test's 1 s renewals
could lose the lease on a slow build machine (novox/hq issue 591, review of #279).

cmd/mesh-controller/acting.go

@@ -66,7 +66,8 @@ type actor struct {
 	resetSaid string
 	// renewEvery and poll, when set, are how often the serving controller renews the lease it holds and
 	// looks again at one another holds, in place of the lease's own: a test's, so two controllers hand the
-	// lease over in a second rather than in a renewal of five (novox/hq issue 591).
+	// lease over in a second rather than in a renewal of five (novox/hq issue 591). A renewal is given
+	// the lease's own RenewEvery to answer however often it is made, so a slow bus does not lose it.
 	renewEvery, poll time.Duration
 }
 
@@ -227,7 +228,7 @@ func (a *actor) serveUnderTheLease(ctx context.Context, inv *inventory.Inventory
 	}
 	say := func(format string, args ...any) { fmt.Printf(format+"\n", args...) }
 	l, err := lease.Open(ctx, api, broker.LeaseBucket, lease.Options{Holder: holderOf(instance),
-		RenewEvery: a.renewEvery, Poll: a.poll, Floor: inv.HighestEpoch, Say: say, Health: controllerHealth, Moved: func(was, floor uint64) {
+		RenewEvery: a.renewEvery, RenewWithin: lease.RenewEvery, Poll: a.poll, Floor: inv.HighestEpoch, Say: say, Health: controllerHealth, Moved: func(was, floor uint64) {
 			a.mu.Lock()
 			defer a.mu.Unlock()
 			a.reset = time.Now()

cmd/mesh-controller/lease_test.go

@@ -57,7 +57,8 @@ func TestTwoControllersOneActs(t *testing.T) {
 
 	// Each renews five times and looks again ten times as often as a serving controller does, so the
 	// handover and the loss below are seen in a second, not in a renewal of five (novox/hq issue 591): what
-	// is checked is the order of events, which does not change with the interval.
+	// is checked is the order of events, which does not change with the interval. Each renewal still has a
+	// serving controller's five seconds to answer (acting.go), so a slow bus does not lose A the lease.
 	const renewEvery, poll = lease.RenewEvery / 5, lease.Poll / 10
 
 	// Controller A takes the lease.

cmd/mesh-controller/plans_follow_test.go

@@ -175,7 +175,7 @@ func TestAPlanFollowedFromTheStoreAnswersWhenItMoves(t *testing.T) {
 	if got.Came != "tier" || got.Plan.Tier != 1 || got.Plan.State != inventory.PlanRolling {
 		t.Fatalf("the wait answered %+v", got)
 	}
-	if waited := time.Since(began); waited > 10*time.Second {
+	if waited := time.Since(began); waited > 3*time.Second {
 		t.Errorf("it answered after %s, not when the plan moved", waited)
 	}
 	out = printed(t, func() error {