Intended behaviour of SET search_path with SQL functions?

=> SHOW search_path;
search_path
-------------
beta
(1 row)

=> CREATE OR REPLACE FUNCTION func_b() RETURNS SETOF int AS $$
SELECT id FROM table_a;
$$ LANGUAGE sql SET search_path = alpha;
ERROR: relation "table_a" does not exist
CONTEXT: SQL function "func_b"

=> \d table_a
Did not find any relation named "table_a".

=> \d alpha.table_a
Table "alpha.table_a"
Column | Type | Modifiers
--------+---------+-----------
id | integer |

If I temporarily create a beta.table_a then I get to create the function
and afterwards it does the right thing. It also works fine with a
pl/pgsql function - presumably it's all down to context on the initial
parse.

I can't think of a way to exploit this maliciously, or do anything other
than cause a little confusion, but I'm not sure it's intentional.

--
Richard Huxton
Archonet Ltd