NOTICE: _outNode: don't know how to print type 715

Hi all,

PostgreSQL gives me a strange message when I try to create a table
with a NOT NULL column.

drop table prova;
DROP
create table prova(
campo1 INTEGER
);
CREATE

drop table prova;
DROP
create table prova(
campo1 INTEGER NOT NULL
);
NOTICE: _outNode: don't know how to print type 715
CREATE
\d prova

Table = prova
+---------------------------+----------------------------------+-------+
| Field | Type | Length|
+---------------------------+----------------------------------+-------+
| campo1 | int4 not null | 4 |
+---------------------------+----------------------------------+-------+

Does someone knows what that message means ?

Thank you,
Jose'