GH#1938 - Ignore unexpected actions in system contract instead of failing

contracts/eosio.system/eosio.system.hpp

@@ -189,9 +189,6 @@ namespace eosiosystem {
                   using undelegatebw = typename delegate_bandwidth<SystemAccount>::undelegatebw;
                   if(code == undelegatebw::get_account() && act == undelegatebw::get_name() ){
                      contract().on( receiver, eosio::unpack_action_data<undelegatebw>() );
-                  } else {
-                     eosio::print("Unexpected action: ", eosio::name{act}, "\n");
-                     eosio_assert( false, "received unexpected action");
                   }
                }
             }