BUG #6101: ALTER TABLE hangs with AccessExclusiveLock

The following bug has been logged online:

Bug reference: 6101
Logged by: Dmitry
Email address: y4gr5rzn(at)gmail(dot)com
PostgreSQL version: 9.0.4
Operating system: Debian i686 2.6.32-5-686-bigmem
Description: ALTER TABLE hangs with AccessExclusiveLock
Details:

ALTER locks the table AccessExclusiveLock and hangs.
I can break it with Ctrl-C in psql, but it 100% reproduces in any session.

Command: ALTER TABLE Amazon.Books ADD COLUMN textsearchable_index_col
tsvector;

Similar reports:
http://archives.postgresql.org/pgsql-admin/2002-04/msg00284.php
http://www.justskins.com/forums/how-to-release-a-133616.html

pg_locks: AccessExclusiveLock granted=f
ps:
postgres 3535 0.0 0.0 50064 652 ? Ss Jul05 0:00 postgres:
al mydb [local] idle in transaction
postgres 22295 0.1 1.0 51804 34028 ? Ss Jul03 7:18 postgres:
al mydb [local] ALTER TABLE waiting

Also, i can submit SQL table description, full pg_locks, pg_class,
pg_stat_activity.