BUG #11703: ERROR: variable not found in subplan target list

The following bug has been logged on the website:

Bug reference: 11703
Logged by: Karl Bartel
Email address: karl(dot)bartel(at)adspert(dot)de
PostgreSQL version: 9.3.5
Operating system: Mac OS X
Description:

The above error occurs when I execute

CREATE TABLE my_table (
my_column text
);

CREATE OR REPLACE FUNCTION func1(tab my_table)
RETURNS int AS $$
SELECT CASE tab.my_column
WHEN 'foobar' THEN 1
END
$$ LANGUAGE sql IMMUTABLE;

CREATE OR REPLACE FUNCTION func2(
tab my_table
)
RETURNS TABLE(ret1 int) AS $$
SELECT func1(tab)
$$ LANGUAGE sql IMMUTABLE;

SELECT 1
FROM my_table,
func2(my_table);

I can reproduce this with the postgres.app on OS 10.8.5:
PostgreSQL 9.3.5 on x86_64-apple-darwin13.3.0, compiled by Apple LLVM
version 5.0 (clang-500.2.79) (based on LLVM 3.3svn), 64-bit

And on my debian machine:
PostgreSQL 9.3.5 on x86_64-unknown-linux-gnu, compiled by gcc (Debian
4.7.2-5) 4.7.2, 64-bit