message: Check strengthening
diff: @@ -101,12 +101,12 @@ bool CheckSpendZcoinTransaction(const CTransaction &tx,
  }
  if (IsZerocoinTxV2(targetDenomination, pubcoinId)) {
  - // After threshold id all spends should be either version 1.5 or 2.0
  - if (spendVersion == ZEROCOIN_TX_VERSION_1)
  + // After threshold id all spends should be strictly 2.0
  + if (spendVersion != ZEROCOIN_TX_VERSION_2)
  return state.DoS(100,
  false,
  NSEQUENCE_INCORRECT,
  - "CTransaction::CheckTransaction() : Error: zerocoin spend should be version 1.5 or 2.0");
  + "CTransaction::CheckTransaction() : Error: zerocoin spend should be version 2.0");
  }
  else {
  // old spends v2.0s are probably incorrect, force spend to version 1
  