It can cause panic while running test data with some special

[absolute8511]

I found the test code below can cause the panic of DB, is any wrong with the test code?

type ritem struct {
	Key   string
	Value []byte
}
	base := []byte{1, 0, 1, 0}
	key := append([]byte{}, base...)
	minKey := []byte{1, 0, 1}

	schema := &memdb.DBSchema{
		Tables: map[string]*memdb.TableSchema{
			"0": &memdb.TableSchema{
				Name: "0",
				Indexes: map[string]*memdb.IndexSchema{
					"id": &memdb.IndexSchema{
						Name:    "id",
						Unique:  true,
						Indexer: &memdb.StringFieldIndex{Field: "Key"},
					},
				},
			},
		},
	}
	mdb, err := memdb.NewMemDB(schema)
	assert.Nil(t, err)

	txn := mdb.Txn(true)
	txn.Insert("0", &ritem{Key: string(key), Value: []byte("1")})
	txn.Insert("0", &ritem{Key: string(append(key, byte(1))), Value: []byte("1")})
	txn.Commit()

	txn = mdb.Txn(false)
	defer txn.Abort()
	resIter, err := txn.LowerBound("0", "id", string(minKey))  // panic happened here
	assert.Nil(t, err)

[absolute8511]

It is related to the issue in hashicorp/go-immutable-radix#28
and could be fixed by the pr hashicorp/go-immutable-radix#35