public function tryLastModified( $modifiedTime ) {
		$clientCache = $this->getHeader( 'If-Modified-Since' );
		if ( $clientCache !== false ) {
			# IE sends sizes after the date like "Wed, 20 Aug 2003 06:51:19 GMT; length=5202"
			# which would break strtotime() parsing.
			$clientCache = preg_replace( '/;.*$/', '', $clientCache );
			$clientCacheTime = @strtotime( $clientCache );
			if ( $modifiedTime <= $clientCacheTime ) {
				header( 'Status: 304 Not Modified', true, 304 );
				return true;
			}
		}
		return false;
	}