[TYPO3] realurl worries

[Martin Kindler]

I've got a mysterious problem while trying to setup realurl for my site. I
have a multilanguage site where I use "locale" as the language switching
GET-parameter.
I setup realurl with the following configuration:

$TYPO3_CONF_VARS['EXTCONF']['realurl']['_DEFAULT'] = array (
	'preVars' => array(
		array(
			'GETvar' => 'locale',
			'valueMap' => array(
				'de' => '0',
				'en' => '1',
				'ru' => '4',
			),
		noMatch => 'bypass',
		),
	),
)

This works for the default language (German) but the language is not
translated to a path element. If I set noMatch to 'null' (the only other
allowed value) it does not work.
If I set noMatch to something else (in my case just 'foo'), it works!!!!

Can someone explain this to me?

Martin

PS: I am using v3.8.1