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