missing optimization - column <> column

Hi

I found some crazy queries in one customer application. These queries are
stupid, but it was surprise for me so there are not some simple optimization

create table foo(a int);
insert into foo select generate_series(1,100000);
analyze foo;
explain select * from foo where a <> a;

It does full scan of foo, although it should be replaced by false in
planner time.

Same issue is a expression a = a .. can be replaced by true

Regards

Pavel