open and closed paths ...

I am using PostgreSQL 7.0.3. I have tried the isopen() function but it
doesn't seem to work (or it is not fully implemented yet).
In my opinion the third record is a closed path but the isopen()
functions return f.
Have I done something wrong, have I got something wrong or is it a bug?
   Hans



shop=# SELECT * FROM temppath;     fieldname
----------------------((1,3),(4,12))((3,1),(2,8),(10,4))((3,1),(2,8),(3,1))((1,1),(2,2),(3,3))
(4 rows)

shop=# INSERT INTO temppath(fieldname) VALUES ('(1,1), (2,3)');
INSERT 51857 1
shop=# SELECT isopen(fieldname) FROM temppath;isopen
--------fffff
(5 rows)