Wait for tier 1's module to be marked taken from its key: the tier moves in one look and the mark comes in the next, so a loaded build node read it between them (group check fcb076c5387f)

cmd/mesh-controller/silent_mid_tier_integration_test.go

@@ -193,9 +193,13 @@ func TestAPlanPassesATierWhoseMachineNeverReportsAfterTheBoundAndSendsTheNextToT
 	if !strings.Contains(moved, "laptop") || strings.Contains(moved, "anchor") {
 		t.Errorf("1160/AC5: the plan says %q; want laptop named silent and not anchor", moved)
 	}
-	if b := plan().Modules["b"]; b == nil || !b.Key {
-		t.Errorf("tier 1's module is not taken from its key: %+v", b)
-	}
+	// The move to tier 1 is saved in one step and the look that marks b taken from its key is the next (release_plan.go
+	// advances the tier, plan_keys.go takeFromKey marks it): read b once that look ran, not in the instant the tier moved,
+	// which a loaded build node shows before it (group check fcb076c5387f).
+	eventually(t, "tier 1's module taken from its key", func() bool {
+		b := plan().Modules["b"]
+		return b != nil && b.Key
+	})
 	// Tier 1's module is taken from its key once that is built, which the walk's look does by itself.
 	heldB.Store(false)
 	askToLook()