fix offset when stopping blockchain

Author: tsahee

core/blockchain.go

@@ -883,7 +883,7 @@ func (bc *BlockChain) Stop() {
 	if !bc.cacheConfig.TrieDirtyDisabled {
 		triedb := bc.stateCache.TrieDB()
 
-		for _, offset := range []uint64{0, 1, bc.cacheConfig.TriesInMemory} {
+		for _, offset := range []uint64{0, 1, bc.cacheConfig.TriesInMemory - 1} {
 			if number := bc.CurrentBlock().NumberU64(); number > offset {
 				recent := bc.GetBlockByNumber(number - offset)
 				if recent.Root() == (common.Hash{}) {