select...where...in...union bug?

Hi,

(1) If I issue the following query:

 SELECT GEOM_CLASS.* FROM GEOM_CLASS

I get the following result:

 +-----+
 | GID |
 +-----+
 |   1 |
 |   2 |
 +-----+

(2) If I issue the following query:

 SELECT GEOM_CLASS.GID FROM GEOM_CLASS WHERE (GEOM_CLASS.GID = 2)
 UNION
 SELECT GEOM_CLASS.GID FROM GEOM_CLASS WHERE (GEOM_CLASS.GID = 1)

I get the following result:

 +-----+
 | GID |
 +-----+
 |   2 |
 |   1 |
 +-----+

(3) Now, if I combine (1) and (2) in the following way:

 SELECT GEOM_CLASS.* FROM GEOM_CLASS WHERE (GEOM_CLASS.GID IN (
  SELECT GEOM_CLASS.GID FROM GEOM_CLASS WHERE (GEOM_CLASS.GID = 2)
  UNION
  SELECT GEOM_CLASS.GID FROM GEOM_CLASS WHERE (GEOM_CLASS.GID = 1)
 ))

I get the following result:

 +-----+
 | GID |
 +-----+
 |   1 |
 +-----+

Shouldn't I get:

 +-----+
 | GID |
 +-----+
 |   1 |
 |   2 |
 +-----+

(4) I do get the above result if I run the following query:

 SELECT GEOM_CLASS.* FROM GEOM_CLASS WHERE (GEOM_CLASS.GID IN (
  SELECT 2 UNION SELECT 1
 ))

thanks in advance, Chuck