UNION/INTERSECT in subselects

Hi, I'm using 7.0.2 and I have a problem with UNION in some subselects,
namely the following works:
select * from a where a.f in (select 1)
but this doesn't:
select * from a where a.f in (select 1 union select 2)

In the grammar we have :
in_expr: SubSelect | ...
but SubSelect doesn't allow UNIONs, only select_clause does.

Could in_expr be changed to use select_clause instead without adverse
ill effects ?

In fact SubSelect is used all over the place, so maybe it's better to
switch select_clause and SubSelect in the definitions for SelectStmt,
select_clause and SubSelect ?

Thanks,
Florent

(Please Cc: me in your answers)