Interesting bug in tablespaces

There is a confusing bug in tablespaces.  Here is examples:

OK, let's create a table with the 3 possible tablespaces of indexes:

test=# create table test(a int4) tablespace loc;
CREATE TABLE
test=# create unique index test_a_idx on test(a);
CREATE INDEX
test=# create unique index test_a_idx2 on test(a) tablespace loc;
CREATE INDEX
test=# create unique index test_a_idx3 on test(a) tablespace pg_default;
CREATE INDEX
test=# \d test     Table "public.test" Column |  Type   | Modifiers
--------+---------+----------- a      | integer |
Indexes:    "test_a_idx" UNIQUE, btree (a)    "test_a_idx2" UNIQUE, btree (a)    "test_a_idx3" UNIQUE, btree (a)
Tablespace: "loc"

test=# select relname, reltablespace from pg_class where relname like 
'test%';   relname   | reltablespace
-------------+--------------- test        |         17229 test_a_idx  |         17229 test_a_idx2 |         17229
test_a_idx3|             0
 
(4 rows)

Note that psql (and pg_dump) will (because of pg_get_indexdef()) think 
that test_a_idx3 is in tablespace 'loc', even though it's in tablespace 
'pg_default'.

Now, let's make it worse:

test=# alter table test set tablespace loc2;
ALTER TABLE
test=# \d test     Table "public.test" Column |  Type   | Modifiers
--------+---------+----------- a      | integer |
Indexes:    "test_a_idx" UNIQUE, btree (a) TABLESPACE loc    "test_a_idx2" UNIQUE, btree (a) TABLESPACE loc
"test_a_idx3"UNIQUE, btree (a)
 
Tablespace: "loc2"

test=# select relname, reltablespace from pg_class where relname like 
'test%';   relname   | reltablespace
-------------+--------------- test        |         17279 test_a_idx  |         17229 test_a_idx2 |         17229
test_a_idx3|             0
 
(4 rows)

Now, it thinks test_a_idx3 is in loc2.  pg_dump will dump it like that 
as well, so when it's restored, test_a_idx3 will be recreated in loc2.

Chris