[wasm] Unable to set Content-Type of 1st http post

#include <QCoreApplication>
#include <QNetworkAccessManager>
#include <QNetworkRequest>
#include <QNetworkReply>
#include <QUrl>

QNetworkAccessManager *g_Manager = nullptr;
void post();

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);    
      QNetworkAccessManager manager;
    g_Manager = &manager;   

      post();
    post();    

      return a.exec();
}

void post()
{
    QEventLoop eventLoop;
    QObject::connect(g_Manager, &QNetworkAccessManager::finished, &eventLoop, &QEventLoop::quit);    

      QNetworkRequest request(QUrl("http://localhost/api/test"));
    request.setHeader(QNetworkRequest::ContentTypeHeader, "application/json");
    QNetworkReply *reply = g_Manager->post(request, "{}");
    eventLoop.exec();    

      reply->deleteLater();
}