BUG #8170: alter user does not accept timestamp output format in certain datestyles and timezones.

The following bug has been logged on the website:

Bug reference: 8170
Logged by: Chris Travers
Email address: chris(dot)travers(at)gmail(dot)com
PostgreSQL version: 9.2.4
Operating system: Debian Linux
Description:

I have a pl/pgsql function which calculates at imestamp and alters a user's
password to be valid for 24 hours pending a password change. When the
datestyle and timezone are set to certain settings this throws an
exception.

Here is an approximation without plpgsql:

db=# show timezone;
TimeZone
--------------
Asia/Jakarta
(1 row)

db=# show datestyle;
DateStyle
---------------
Postgres, DMY
(1 row)

db=# select now();
now
-------------------------------------
Mon 20 May 11:39:24.273508 2013 WIT
(1 row)

db=# select 'ALTER USER ' || quote_ident('chris') || ' with valid until ' ||
quote_literal(now() + '1 day');
?column?
------------------------------------------------------------------------
ALTER USER chris with valid until 'Tue 21 May 11:41:14.58554 2013 WIT'
(1 row)

db=# ALTER USER chris with valid until 'Tue 21 May 11:41:14.58554 2013
WIT';
ERROR: invalid input syntax for type timestamp with time zone: "Tue 21 May
11:41:14.58554 2013 WIT"

This worked before with different timezones with the same datestyle. Why is
this failing?