Hold the controller walk's key in the own-path test and read its walk again before ending it (issue 1931)

cmd/mesh-controller/batches_integration_test.go

@@ -641,6 +641,14 @@ func TestAMergeOnTheControllersPathNeverSharesABatch(t *testing.T) {
 	// A catalogue walk waiting for its word when an own-path batch is cut keeps waiting beside the own-path
 	// walk, is not folded into it, and its word is taken meanwhile: it starts once the own-path walk ended.
 	catalogueWalk := ws[0]
+	// The controller's second walk keeps its key unbuilt, so it stays started as it did while its build ran; with the
+	// stand-in builder's key done at once one step would carry it to done and nothing would be beside the catalogue walk.
+	wholeKeys, held := openPlanKeys, &atomic.Bool{}
+	held.Store(true)
+	openPlanKeys = func() (planKeyReads, func(), error) {
+		all, done, err := wholeKeys()
+		return keysHolding{all, "mesh-controller", held, fpOfModuleAt("mesh-controller", "k2")}, done, err
+	}
 	hear(t, open, repoMerge("mesh-controller", "k2", t0.Add(4*time.Minute)), t0.Add(4*time.Minute))
 	cutAt(t, open, t0.Add(6*time.Minute))
 	ws, _ = walks(t, open)
@@ -659,7 +667,11 @@ func TestAMergeOnTheControllersPathNeverSharesABatch(t *testing.T) {
 	if len(*asked) != before {
 		t.Fatalf("the catalogue walk started beside the controller's: asked %v", (*asked)[before:])
 	}
-	own2 := ws[0]
+	// Read again: the step above wrote the walk (what its key waits for), so the copy read at its cut is stale.
+	own2, err := open.inventory.PlanByID(ctx, ws[0].ID)
+	if err != nil {
+		t.Fatal(err)
+	}
 	own2.State = inventory.PlanDone
 	if err := open.inventory.SavePlan(ctx, &own2); err != nil {
 		t.Fatal(err)