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