Column reported as not existing when referenced in subselect

[rswheeldon]

Describe the bug

I have a table with a column on it, that pg-mem refuses to realise exists in a subselect although it's perfectly happy to return the same column in the main statement.

column "f.x" does not exist

🐜 This seems to be an execution error, which means that your request syntax seems okay,
    but the resulting statement cannot be executed → Probably not a pg-mem error.

*️⃣ Reconsituted failed SQL statement: SELECT x , (SELECT (count ((1)) )  FROM foo   WHERE (x >= f .x) )  FROM foo  AS f

To Reproduce

create table foo(x integer);
insert into foo values (3), (5);
select x, (select count(1) from foo where x >= f.x) from foo f;

pg-mem version

2.8.1 (and current sand box at time of writing)