BUG #4253: to_tsvector: error with some configurations

The following bug has been logged online:

Bug reference:      4253
Logged by:          Giorgio Valoti
Email address:      giorgio_v@mac.com
PostgreSQL version: 8.3.3
Operating system:   Mac OS X 10.5.3
Description:        to_tsvector: error with some configurations
Details:

Using every language containing the "a grave" letter (c3 a0) causes an error
when the function "ts_vector" is invoked.

test=> select to_tsvector('italian','prova');
ERROR:  invalid byte sequence for encoding "UTF8": 0xc3
HINT:  This error can also happen if the byte sequence does not match the
encoding expected by the server, which is controlled by "client_encoding".

test=> select to_tsvector('french','prova');
ERROR:  invalid byte sequence for encoding "UTF8": 0xc3
HINT:  This error can also happen if the byte sequence does not match the
encoding expected by the server, which is controlled by "client_encoding".

test=> select to_tsvector('portuguese','prova');
ERROR:  invalid byte sequence for encoding "UTF8": 0xc3
HINT:  This error can also happen if the byte sequence does not match the
encoding expected by the server, which is controlled by "client_encoding".