Fix IsInitialBlockDownload to play nice with testnet

src/main.cpp

@@ -1384,7 +1384,7 @@ bool IsInitialBlockDownload()
     if (lockIBDState)
         return false;
     bool state = (chainActive.Height() < pindexBestHeader->nHeight - 24 * 6 ||
-            pindexBestHeader->GetBlockTime() < GetTime() - nMaxTipAge);
+            std::max(chainActive.Tip()->GetBlockTime(), pindexBestHeader->GetBlockTime()) < GetTime() - nMaxTipAge);
     if (!state)
         lockIBDState = true;
     return state;