BUG #6722: Debugger broken?

The following bug has been logged on the website:

Bug reference: 6722
Logged by: Jan-Peter Seifert
Email address: jan-peter(dot)seifert(at)gmx(dot)de
PostgreSQL version: 9.1.4
Operating system: Windows 7 Enterprise (64-bit)
Description:

Hello,

it seems that the debugger doesn't work with current minor versions of
PostgreSQL.

I don't even get the debugging option shown here:
http://stackoverflow.com/questions/7865615/debug-postgresql-function-using-pgadmin

It could be connected to these changes:
http://git.postgresql.org/gitweb/?p=pldebugger.git;a=log

I activated the debugger in postgresql.conf and restarted the server(s)):
shared_preload_libraries = '$libdir/plugins/plugin_debugger.dll'

As there only exists the contrib-script I tried to execute this: c:\Program
Files\PostgreSQL\9.1\share\contrib\pldbgapi.sql

I only get a function not found ( in debugger.dll ) error:

FEHLER: konnte Funktion »plpgsql_oid_debug« nicht in Datei »C:/Program
Files/PostgreSQL/9.1/lib/plugins/plugin_debugger.dll« finden
SQL Status:42883

If I switch to this it works:
CREATE OR REPLACE FUNCTION pldbg_oid_debug( OID ) RETURNS INTEGER AS
'$libdir/plugins/plugin_debugger' LANGUAGE C STRICT;

It's the same with 8.4.12 ( 32-bit ) and 9.0.8 ( 64-bit ). It's the very
same install script for each version.
In 8.4.12 I also have these two files:
c:\Program Files (x86)\PostgreSQL\8.4\share\contrib\pldbgapi--1.0.sql
and
c:\Program Files
(x86)\PostgreSQL\8.4\share\contrib\pldbgapi--unpackaged--1.0.sql
Obviously they are for PostgreSQL 9.1.
The first says install with 'CREATE EXTENSION pldbgapi'
There's no such extension - neither in Windows nor Ubuntu ( One click
installer and aptitude ) nor in the docs.

With best regards,

Peter