History-query comments and minor refactor

src/Stratis.Features.SQLiteWalletRepository/Tables/HDTransactionData.cs

@@ -271,14 +271,17 @@ END Amount
                     ,       t.Address AS ReceiveAddress
                     ,       t.OutputBlockHeight as BlockHeight
                     FROM    HDTransactionData AS t
+                    -- We want to skip any rows that join up to this sub-query but only for non-staking receives.
+                    -- The idea is that any address appearing as both source and destination would otherwise be a change address that should be skipped.
                     LEFT    JOIN (
                             SELECT  DISTINCT SpendTxId, Address 
                             FROM    HDTransactionData AS t2
                             WHERE   t2.WalletId = {strWalletId} AND t2.SpendTxId is not null and t2.AccountIndex = {strAccountIndex}) t2					
                     ON      t2.SpendTxId = t.OutputTxId
                     AND     t2.Address = t.Address
+                    AND     t.OutputTxIsCoinbase = 0 -- Don't join up if staking.
                     WHERE   t.WalletId = {strWalletId} AND t.AccountIndex = {strAccountIndex}{((address == null) ? "" : $@" AND t.Address = {strAddress}")}
-                    AND     (t.OutputTxIsCoinbase != 0 OR t2.SpendTxId IS NULL){(!forCirrus ? "" : $@"
+                    AND     t2.SpendTxId IS NULL /* Not joining up */{(!forCirrus ? "" : $@"
                     AND     t.OutputTxIsCoinbase = 0")}
                     GROUP   BY t.OutputTxId
                     UNION   ALL";

src/Stratis.Features.SQLiteWalletRepository/Tables/HDWallet.cs

@@ -1,4 +1,5 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 using System.Linq;
 using NBitcoin;
 using SQLite;
@@ -164,13 +165,13 @@ internal ChainedHeader GetFork(ChainedHeader chainTip)
 
             var blockLocator = new BlockLocator()
             {
-                Blocks = this.BlockLocator.Split(',').Select(strHash => uint256.Parse(strHash)).ToList()
+                Blocks = this.BlockLocator.Split(',', System.StringSplitOptions.RemoveEmptyEntries).Select(strHash => uint256.Parse(strHash)).ToList()
             };
 
             List<int> locatorHeights = ChainedHeaderExt.GetLocatorHeights(this.LastBlockSyncedHeight);
 
             // Find a locator block at or below the chain tip.
-            for (int i = 0; i < locatorHeights.Count; i++)
+            for (int i = 0; i < Math.Min(locatorHeights.Count, blockLocator.Blocks.Count); i++)
             {
                 if (chainTip.Height < locatorHeights[i])
                     continue;