BUG #1522: there's a syntax error using psql, distinct

The following bug has been logged online:

Bug reference:      1522
Logged by:          DIEGO URRA
Email address:      diegomann@yahoo.com
PostgreSQL version: 8.0
Operating system:   REDHAT 6.2
Description:        there's a syntax error using psql, distinct
Details:

hi!

select distinct(id) from results;
works fine

select distinct(id) || 'xyz' from results;
works fine

select 'abc' || distinct(id) || 'xyz' from resuls;
syntax error

is this a bug? thanks in advance
DIEGO URRA