BUG #2692: psql sends natively-localized strings to database without setting client_encoding first

The following bug has been logged online:

Bug reference:      2692
Logged by:          Sergiy Vyshnevetskiy
Email address:      serg@vostok.net
PostgreSQL version: 8.1.4
Operating system:   FreeBSD-6 stable
Description:        psql sends natively-localized strings to database
without setting client_encoding first
Details:

psql mixes natively-localized string in SQL commands without setting
client_encoding first. Looks like we _really_ need some code in configure
script to find acceptable native names for our database charsets.

%zsh 1 11:27 serg@serg p0 /home/serg
set | egrep -a '^LANG|^LC_|^MM_CHAR'
LANG=ru_RU.KOI8-R
MM_CHARSET=KOI8-R
%zsh 0 11:27 serg@serg p0 /home/serg
psql -l
ERROR:  invalid byte sequence for encoding "UTF8": 0xe9cdd1
%zsh 1 11:27 serg@serg p0 /home/serg
psql -d postgres
SET
Welcome to psql 8.1.4, the PostgreSQL interactive terminal.

Type:  \copyright for distribution terms
       \h for help with SQL commands
       \? for help with psql commands
       \g or terminate with semicolon to execute query
       \q to quit

#psql  = serg@[local]:5432 postgres
\encoding KOI8
#psql  = serg@[local]:5432 postgres
\l
         Список баз данных
    Имя     | Владелец | Кодировка
------------+----------+-----------
 postgres   | pgsql    | UTF8
 template0  | pgsql    | UTF8
 template1  | pgsql    | UTF8
(записей: 3)

#psql  = serg@[local]:5432 postgres