Have anchor report on tier 1's send in the rollout test only once the plan keeps when it was sent (issue 1938, after issue 1931)

cmd/mesh-controller/rollout_events_test.go

@@ -220,6 +220,12 @@ func TestARolloutAdvancesOnEventsAndAReplacedControllerResumesIt(t *testing.T) {
 		defer mu.Unlock()
 		return len(sends) == 2
 	})
+	// anchor reports on tier 1's send only once the plan keeps when it was sent: a report heard before that reads as one
+	// on the earlier send, and anchor would be named silent (a machine applies for longer than a save takes).
+	eventually(t, "tier 1's send kept in the plan", func() bool {
+		b := plan().Modules["b"]
+		return b != nil && b.SentAt != nil
+	})
 	reports("anchor")
 
 	// laptop never reports: its key expires and the new controller names it silent, which ends the rollout.