Problem with dropping a tablespace

Hello,

I'm unable to drop a recently created tablespace (the partition on which the 
tablespace relies on, run out of space - postgresql seems to have a problem, 
now):


template1=# drop tablespace disk1;
ERROR:  tablespace "disk1" is not empty


Huh? Okay...lets dig into...


template1=# select oid from pg_tablespace where spcname = 'disk1';
    oid
-----------
 594611987
(1 row)



template1=# select * from pg_tablespace_databases(594611987);
 pg_tablespace_databases
-------------------------
 595675173
(1 row)



Aha...so there seems to be a database associated to this tablespace - lets see 
which one - 

template1=# select * from pg_database where oid = 595675173;
 datname | datdba | encoding | datistemplate | datallowconn | datlastsysoid | 
datvacuumxid | datfrozenxid | dattablespace | datconfig | datacl
---------+--------+----------+---------------+--------------+---------------+--------------+--------------+---------------+-----------+--------
(0 rows)



Mhh. Nothing.



How may I delete the tablespace manually?



Best regards

Oliver