version mismatch detection doesn't work

Hackers,

Seems the functionality to detect old versions of the postmaster with
newer psql doesn't work. Here, server is 7.2.1:

$ psql alvherre
ERROR: parser: parse error at or near "."
Welcome to psql 7.3b1, the PostgreSQL interactive terminal.

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

alvherre=> select version();
version
-------------------------------------------------------------
PostgreSQL 7.2.1 on i686-pc-linux-gnu, compiled by GCC 2.96
(1 row)

alvherre=>

--
Alvaro Herrera (<alvherre[a]atentus.com>)
"Nunca confiaré en un traidor. Ni siquiera si el traidor lo he creado yo"
(Barón Vladimir Harkonnen)