System Property variables processed twice in calculation of effective properties

static SurefireProperties calculateEffectiveProperties( Properties systemProperties,
                                                            Map<String, String> systemPropertyVariables,
                                                            Properties userProperties, SurefireProperties props )
    {
        SurefireProperties result = new SurefireProperties();
        result.copyPropertiesFrom( systemProperties );

        result.copyPropertiesFrom( props );

        copyProperties( result, systemPropertyVariables );
        copyProperties( result, systemPropertyVariables );

        // We used to take all of our system properties and dump them in with the
        // user specified properties for SUREFIRE-121, causing SUREFIRE-491.
        // Not gonna do THAT any more... instead, we only propagate those system properties
        // that have been explicitly specified by the user via -Dkey=value on the CLI

        result.copyPropertiesFrom( userProperties );
        return result;
    }