Unable to switch between environment in karate feature file

As per KARATE documentatoion we should use System.setProperty() to set env in test case level, But that option is not working in karate 1.2.0 (Didn't verify in previous versions)

Feature

Feature: Testing env changing
  Scenario: Reading base url of different env
  * print 'Before changing env...---> '+ karate.env
  * print 'Testing karate...'
  * print baseUrl
  * java.lang.System.setProperty("karate.env","STAGE")
  * def newevn = java.lang.System.getProperty('karate.env')
  * print 'After changing env...---> '+ newevn
  * def fun = call read('file:karate-config.js') 
  * print 'Changed env...---> '+ fun.baseUrl

Karate-Config.js file-

function fn() {
  karate.configure('connectTimeout', 5000);
  karate.configure('readTimeout', 5000);
  var env = karate.env;
  karate.log('karate.env system property was:', env);

  var baseUrl = 'testingbase.com';
  karate.log('Env---->' + env)
  var port = karate.properties['demo.server.port'] || '8080';
  var protocol = 'http';

  var config = {
    env: env,
    baseUrl: 'https://localapi.abc123.example.com/api/v1/validate/customerid',
    apiKey: ''
  }
  if (karate.properties['demo.server.https'] === 'true') {
    protocol = 'https';
    karate.configure('ssl', true);
  }
  var config = { demoBaseUrl: protocol + '://127.0.0.1:' + port };
  if (env== 'mock') {
    // karate.configure('callSingleCache', { minutes: 1 });
    // 'callSingle' is guaranteed to run only once even across all threads
    //var result = karate.callSingle('classpath:demo/headers/common-noheaders.feature', config);
    // and it sets a variable called 'authInfo' used in headers-single.feature
   // config.authInfo = { authTime: result.time, authToken: result.token };
  }
  else if(env=='BETA'){
 config.baseUrl='tetsing.beta.base.com';

  }
  else if(env=='STAGE'){
config.baseUrl='tetsing.stage.base.com';

  }
  return config;
}