Fix bootstrap epoch calculation

Author: hanabi1224

certstore/snapshot.go

@@ -153,7 +153,7 @@ func importSnapshotToDatastoreWithTestingPowerTableFrequency(ctx context.Context
 			if cert.ECChain == nil || len(cert.ECChain.TipSets) == 0 {
 				return fmt.Errorf("invalid certificate at first instance %d", cert.GPBFTInstance)
 			}
-			snapshotBootstrapEpoch := cert.ECChain.Base().Epoch
+			snapshotBootstrapEpoch := cert.ECChain.Base().Epoch + m.EC.Finality
 			if m.BootstrapEpoch != snapshotBootstrapEpoch {
 				// Delete entries that are written in `OpenOrCreateStore` above.
 				// Note that if the provided database is non-empty, `OpenOrCreateStore` should

certstore/snapshot_test.go

@@ -84,7 +84,7 @@ func Test_SnapshotExportImportRoundTrip(t *testing.T) {
 
 	generatedChain, err := subject.Generate(ctx, certChainLength)
 	require.NoError(t, err)
-	m.BootstrapEpoch = generatedChain[0].ECChain.Base().Epoch
+	m.BootstrapEpoch = generatedChain[0].ECChain.Base().Epoch + m.EC.Finality
 
 	ds1 := datastore.NewMapDatastore()
 	cs, err := OpenOrCreateStore(ctx, ds1, generatedChain[0].GPBFTInstance, initialPowerTable)