D22: every restore puts the data back exactly on failure and after a power cut (R-1177, R-1195); whole restore asks the unit first (R-1178); no mirror during a restore (R-1180); W22 restore refusals in Hungarian; unreleased

controller/internal/backup/r102_tier2_unit_test.go

@@ -2,6 +2,7 @@ package backup
 
 import (
 	"context"
+	"errors"
 	"io"
 	"log"
 	"os"
@@ -213,7 +214,7 @@ func TestR102_Tier2UnitRestoreTakesTheSingleWriterFlag(t *testing.T) {
 	if err == nil {
 		t.Fatal("a second restore started while one was in flight")
 	}
-	if !strings.Contains(err.Error(), "already in progress") {
+	if !errors.Is(err, ErrRestoreBusy) {
 		t.Errorf("refusal = %v, want the single-writer refusal", err)
 	}
 	if f.fake.stopped {