Not found column for duplicate columns in JOIN ON section

[4ertus2]

Cannot resolve duplicated column from right table of JOIN.

create table t(a Nullable(Int64), b Nullable(Int64), c Nullable(String)) engine = Memory;
create table s(a Nullable(Int64), b Nullable(Int64), c Nullable(String)) engine = Memory;

insert into t values(1,1,'a'), (2,2,'b');
insert into s values(1,1,'a');

select * from t left outer join s on t.a = s.a;
1       1       a       1       1       a
2       2       b       \N      \N      \N

select * from t left outer join s on t.a = s.a and t.a = s.b;
1       1       a       1       1       a
2       2       b       \N      \N      \N

select * from t left outer join s on t.a = s.a and t.a = s.a;
Code: 10. DB::Exception: Received from localhost:9000, 127.0.0.1. DB::Exception: Not found column s.a in block. There are only columns: s.b, s.c. 

select * from t left outer join s on t.a = s.a and t.b = s.a;
Code: 10. DB::Exception: Received from localhost:9000, 127.0.0.1. DB::Exception: Not found column s.a in block. There are only columns: s.b, s.c.

[4ertus2]

Possibly related errors #4222 #971

[4ertus2]

fixed in master