evaluation context stack is broken

#include <QCoreApplication>
#include <QtScript>
#include <QDebug>

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    QScriptEngine *engine = new QScriptEngine(&a);
    QScriptContext *ctx = engine->pushContext();
    ctx->activationObject().setProperty("Egon", engine->newVariant("Olsen"));
    qDebug() << engine->evaluate("Egon").toString();
    engine->pushContext();
    qDebug() << engine->evaluate("Egon").toString();
    engine->popContext();
    engine->popContext();
    return 0;
}

"Olsen" 
"Olsen"

"Olsen" 
"ReferenceError: Can't find variable: Egon"