Bug in contrib/intagg int_array_enum() ?

I'm seeing some strange behaviour using the int_array_enum function in
contrib/intagg.

It seems when i set the array to an empty array by hand doing update set
level_2_ids = '{}' then int_array_enum generates some odd data:

slo=> select * from (select int_array_enum(level_2_ids) as l2,level_2_ids from cache where key_id = 900) as x where level_2_ids = '{}';
l2 | level_2_ids
------------+-------------
0 | {}
23 | {}
1 | {}
0 | {}
5541 | {}
28 | {}
1 | {}
0 | {}
23 | {}
1 | {}
0 | {}
42 | {}
100932 | {}
0 | {}
0 | {}
2113601536 | {}
589827 | {}
1583362 | {}
800 | {}
4120 | {}
1104836463 | {}
1075191249 | {}
32 | {}
1 | {}
0 | {}
23 | {}
2 | {}
0 | {}
(28 rows)

--
greg