I would say that it is either declared explicitly in the themes ‘header.php’ file, and that in the ‘wp_config.php’ the style-sheet-path global variable is set. Check those locations first, then check the ‘functions.php’ for the theme if that doesn’t work.
Check here for the style-sheet variable stuff, under the ‘Hardcode your Template Path and Stylesheet Path’ section: http://digwp.com/2009/07/optimize-wordpress-performance-with-the-wp-config-php-file/
It also appears that the ‘testing’ sub-domain redirected to the same location on the main domain – you probably don’t have that redirect, just change the values when you find them!!!
Let us know if you track it down…