save block b4 apply; track stale apphash

mempool/mempool.go

@@ -282,8 +282,7 @@ func (mem *Mempool) collectTxs(maxTxs int) []types.Tx {
 // NOTE: this should be called *after* block is committed by consensus.
 // NOTE: unsafe; Lock/Unlock must be managed by caller
 func (mem *Mempool) Update(height int, txs []types.Tx) {
-	//	mem.proxyMtx.Lock()
-	//	defer mem.proxyMtx.Unlock()
+	// TODO: check err ?
 	mem.proxyAppConn.FlushSync() // To flush async resCb calls e.g. from CheckTx
 
 	// First, create a lookup map of txns in new txs.