BUG #5056: SQLDescribeColW for function returning a result set incorrectly setting sql_nullable

The following bug has been logged online:

Bug reference: 5056
Logged by: the6campbells
Email address: the6campbells(at)gmail(dot)com
PostgreSQL version: 8.4.1
Operating system: windows
Description: SQLDescribeColW for function returning a result set
incorrectly setting sql_nullable
Details:

create table TSET1 (RNUM integer not null, C1 integer, C2 char(3));

create function PRES ( )
returns setof TSET1 as
'
select RNUM, C1, C2 from TSET1;
' LANGUAGE 'sql'
;

in ODBC test sqlPrepare { call pres } then describe the columns. first
column should be SQL_NO_NULLS not NULLABLE.

Describe Column All:
icol, szColName, *pcbColName, *pfSqlType, *pcbColDef, *pibScale,
*pfNullable
1, rnum, 4, SQL_INTEGER=4, 10, 0, SQL_NULLABLE=1
2, c1, 2, SQL_INTEGER=4, 10, 0, SQL_NULLABLE=1
3, c2, 2, SQL_WCHAR=-8, 3, 0, SQL_NULLABLE=1