PPCoin: Fix pausing issues of initial block download

        around the latest proof-of-work block

src/main.cpp

@@ -2064,7 +2064,8 @@ bool ProcessBlock(CNode* pfrom, CBlock* pblock)
             pfrom->PushGetBlocks(pindexBest, GetOrphanRoot(pblock2));
             // ppcoin: getblocks may not obtain the ancestor block rejected
             // earlier by duplicate-stake check so we ask for it again directly
-            pfrom->AskFor(CInv(MSG_BLOCK, WantedByOrphan(pblock2)));
+            if (!IsInitialBlockDownload())
+                pfrom->AskFor(CInv(MSG_BLOCK, WantedByOrphan(pblock2)));
         }
         return true;
     }
@@ -2909,6 +2910,10 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
             if (pindex->GetBlockHash() == hashStop)
             {
                 printf("  getblocks stopping at %d %s (%u bytes)\n", pindex->nHeight, pindex->GetBlockHash().ToString().substr(0,20).c_str(), nBytes);
+                // ppcoin: tell downloading node about the latest block if it's
+                // without risk being rejected due to stake connection check
+                if (hashStop != hashBestChain && pindex->GetBlockTime() + STAKE_MIN_AGE > pindexBest->GetBlockTime())
+                    pfrom->PushInventory(CInv(MSG_BLOCK, hashBestChain));
                 break;
             }
             pfrom->PushInventory(CInv(MSG_BLOCK, pindex->GetBlockHash()));