Be more conservative: check all transactions in blocks after last checkpoint.

src/main.cpp

@@ -35,7 +35,6 @@ map<COutPoint, CInPoint> mapNextTx;
 map<uint256, CBlockIndex*> mapBlockIndex;
 uint256 hashGenesisBlock("0x000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f");
 static CBigNum bnProofOfWorkLimit(~uint256(0) >> 32);
-const int nInitialBlockThreshold = 120; // Regard blocks up until N-threshold as "initial download"
 CBlockIndex* pindexGenesisBlock = NULL;
 int nBestHeight = -1;
 CBigNum bnBestChainWork = 0;
@@ -826,7 +825,7 @@ int GetNumBlocksOfPeers()
 
 bool IsInitialBlockDownload()
 {
-    if (pindexBest == NULL || nBestHeight < (Checkpoints::GetTotalBlocksEstimate()-nInitialBlockThreshold))
+    if (pindexBest == NULL || nBestHeight < Checkpoints::GetTotalBlocksEstimate())
         return true;
     static int64 nLastUpdate;
     static CBlockIndex* pindexLastBest;
@@ -976,10 +975,10 @@ bool CTransaction::ConnectInputs(map<uint256, pair<CTxIndex, CTransaction> > inp
                     if (pindex->nBlockPos == txindex.pos.nBlockPos && pindex->nFile == txindex.pos.nFile)
                         return error("ConnectInputs() : tried to spend coinbase at depth %d", pindexBlock->nHeight - pindex->nHeight);
 
-            // Skip ECDSA signature verification when connecting blocks (fBlock=true) during initial download
-            // (before the last blockchain checkpoint). This is safe because block merkle hashes are
+            // Skip ECDSA signature verification when connecting blocks (fBlock=true)
+            // before the last blockchain checkpoint. This is safe because block merkle hashes are
             // still computed and checked, and any change will be caught at the next checkpoint.
-            if (!(fBlock && IsInitialBlockDownload()))
+            if (!(fBlock && (nBestHeight < Checkpoints::GetTotalBlocksEstimate())))
             {
                 bool fStrictOpEval = true;
                 // This code should be removed when OP_EVAL has