8.1beta timezone question

I may have missed it in the docs, but were certain timestamp abbreviations
phased out between 8.0.3 and 8.1 beta1?

eg.
(8.0.3)
#SELECT TIMESTAMP '2001-02-16 20:38:40' AT TIME ZONE 'PST';
timezone
-------------------------
16/02/2001 20:38:40 PST

(8.1beta1)
#SELECT TIMESTAMP '2001-02-16 20:38:40' AT TIME ZONE 'PST';
ERROR: time zone "PST" not recognised

The tzname still works fine, though:
SELECT TIMESTAMP '2001-02-16 20:38:40' AT TIME ZONE 'Canada/Pacific';
timezone
-------------------------
16/02/2001 20:38:40 PST

Or maybe there is a setting that I neglected to adjust to make this work on
8.1beta1? The same error occurs with several other timezone abbreviations that I
tried.

Cheers,

Bricklen
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