Optimizer trace: multi-part ranges are not printed correctly

create table t1 (a int, b int, key(a,b));

insert into t1 values (1,1),(2,2);

set optimizer_trace=1;

explain select * from t1 where a in (5,6) and b >= 10;

select * from information_schema.optimizer_trace;

                  "analyzing_range_alternatives": {

                    "range_scan_alternatives": [

                      {

                        "index": "a",

                        "ranges": [

                          "(5,10) <= (a,b) <= (5)",

                          "(6,10) <= (a,b) <= (6)"

                        ],