message: Special case onblock to eliminate log message on every block.
diff: @@ -497,6 +497,11 @@ void add_data( bsoncxx::builder::basic::document& act_doc, mongocxx::collection&
  } catch( std::exception& e ) {
  ilog( "Unable to convert action.data to ABI: ${s}::${n}, std what: ${e}",
  ("s", act.account)( "n", act.name )( "e", e.what()));
  + } catch (fc::exception& e) {
  + if (act.name != "onblock") { // eosio::onblock not in original eosio.system abi
  + ilog( "Unable to convert action.data to ABI: ${s}::${n}, fc exception: ${e}",
  + ("s", act.account)( "n", act.name )( "e", e.to_detail_string()));
  + }
  } catch( ... ) {
  ilog( "Unable to convert action.data to ABI: ${s}::${n}, unknown exception",
  ("s", act.account)( "n", act.name ));
  