message: small bugfix: don't update requestim in case of zero change to refund
diff: @@ -296,7 +296,7 @@ namespace eosiosystem {
  bool need_deferred_trx = false;
  if ( req != refunds_tbl.end() ) { //need to update refund
  refunds_tbl.modify( req, 0, [&]( refund_request& r ) {
  - if ( net_balance <= asset(0) || cpu_balance <= asset(0) ) {
  + if ( net_balance < asset(0) || cpu_balance < asset(0) ) {
  r.request_time = now();
  }
  r.net_amount -= net_balance;
  