BUG #3363: Unable to load a plugin/library using -c switch to the psql

The following bug has been logged online:

Bug reference: 3363
Logged by: Gurjeet Singh
Email address: singh(dot)gurjeet(at)gmail(dot)com
PostgreSQL version: 8.3devel
Operating system: Windows
Description: Unable to load a plugin/library using -c switch to the
psql
Details:

The following command fails:

psql postgres test -X -c "load '$libdir/plugins/index_adviser.dll';"

Here, 'test' user (non-superuser) is trying to connect to 'postgres'
database, and wishes to load a plugin as the first step.

But if the same 'load' command is fired by the same user after log-in
using psql, then the command succeeds.

postgres=> load '$libdir/plugins/index_adviser.dll';
NOTICE: IND ADV: Loaded; PID: 1164
LOAD
postgres=>