message: Fix bug where stale lookahead blocks are nto properly detected
diff: @@ -1146,7 +1146,7 @@ void ThreadStakeMiner(CWallet *pwallet)
  // CheckStake also does CheckBlock and AcceptBlock to propogate it to the network
  bool validBlock = false;
  while(!validBlock) {
  - if (pindexPrev->GetBlockHash() != beginningHash) {
  + if (chainActive.Tip()->GetBlockHash() != beginningHash) {
  //another block was received while building ours, scrap progress
  LogPrint("staker", "ThreadStakeMiner(): Valid future PoS block was orphaned before becoming valid");
  break;
  