Could not modify dropdown value from survey correctly if choices are loading from web

[andrewtelnov]

If dropdown value has a value initially, for example defaultValue, and survey.data = newData; or survey.mergeData(newData); is called when choices are loading from a server async, then a new value from survey.data is not set correctly. Here is the example and code:

const json = {
  "elements": [{
    "type": "dropdown",
    "name": "country",
    "defaultValue": "France",
    "choicesByUrl": {
      "url": "https://surveyjs.io/api/CountriesExample",
      "valueName": "name"
    }
  }],
  "showQuestionNumbers": false
}
const survey = new Survey.Model(json);
survey.mergeData({country: "Italy"});

The expected value is Italy, but it will be the default value "France".