After merge fix

select hex(convert(s1 using latin1)) from t1;

hex(convert(s1 using latin1))

7F

drop table t1;

create table t1 (a varchar(15) character set ascii not null, b int);

insert into t1 values ('a',1);

select concat(a,if(b<10,_ucs2 0x0061,_ucs2 0x0062)) from t1;