clientv3/integration: match grpc.ErrClientConnClosing in TestKVNewAfterClose

Signed-off-by: Gyu-Ho Lee <gyuhox@gmail.com>

clientv3/integration/kv_test.go

@@ -472,8 +472,9 @@ func TestKVNewAfterClose(t *testing.T) {
 
 	donec := make(chan struct{})
 	go func() {
-		if _, err := cli.Get(context.TODO(), "foo"); err != context.Canceled {
-			t.Fatalf("expected %v, got %v", context.Canceled, err)
+		_, err := cli.Get(context.TODO(), "foo")
+		if err != context.Canceled && err != grpc.ErrClientConnClosing {
+			t.Fatalf("expected %v or %v, got %v", context.Canceled, grpc.ErrClientConnClosing, err)
 		}
 		close(donec)
 	}()