BUG #1459: Connection hangs when other connection is not committed

The following bug has been logged online:

Bug reference:      1459
Logged by:          Rainer Frey
Email address:      rainer.frey@inxmail.de
PostgreSQL version: 8.0.1
Operating system:   Redhat Linux 9, Kernel 2.4.20-8, AMD Sempron 2500+, 1GB
RAM
Description:        Connection hangs when other connection is not committed
Details:

There seems to be a locking problem when not using autocommit. I came across
this in a relatively complex Java application, but could reproduce it with
the following scenario: (user test has priviledge to create db)
createdb -U test -W testdb
psql -U test -W testdb
CREATE TABLE test_table (id integer);
ALTER TABLE test_table ADD test integer;

now start another client session, disable autocommit:
psql -U test -W testdb
\set AUTOCOMMIT off
SELECT * FROM test_table;

Back in the first session, try to add another column:
ALTER TABLE test_table ADD test1 integer;

This hangs forever, until I commit session 2.
A select should not lock a table even when it is not committed.