BUG #3833: Index remains when table is dropped

The following bug has been logged online:

Bug reference: 3833
Logged by: Laurenz Albe
Email address: laurenz(dot)albe(at)wien(dot)gv(dot)at
PostgreSQL version: 8.2.5
Operating system: RedHat Enterprise Linux 3
Description: Index remains when table is dropped
Details:

Two concurrent sessions perform statements against one database. The
sessions are named s1 and s2 in this example.

s1=> CREATE TABLE x(i integer);

s2=> BEGIN;
s2=> CREATE UNIQUE INDEX x_pkey ON x(i);

s1=> DROP TABLE x;
(Session hangs)

s2=> COMMIT;

Now Session s1 will unblock and succeed in dropping the table. The index,
however, remains in pg_class, pg_depend, and pg_index.

"DROP INDEX x_pkey" will lead to an error like this:
ERROR: could not open relation with OID 65615
The OID here is the one of the dropped table.