message: RPC: hack MintToTxIn to allow spending an already spent zpiv on regtest
diff: @@ -4762,7 +4762,7 @@ bool CWallet::MintToTxIn(CZerocoinMint zerocoinSelected, int nSecurityLevel, con
  return error("%s : %s", __func__, receipt.GetStatusMessage());
  }
  - if (IsSerialKnown(spend.getCoinSerialNumber())) {
  + if (Params().NetworkID() != CBaseChainParams::REGTEST && IsSerialKnown(spend.getCoinSerialNumber())) {
  //Tried to spend an already spent zPIV
  receipt.SetStatus(_("The coin spend has been used"), ZPIV_SPENT_USED_ZPIV);
  