QtWebEngine prompts for location permission three times

The attached zip is the simplebrowser example from Qt 5.10.1 with very minor changes. The feature request signal is connected to a slot that always unconditionally grants whatever feature is requested. Also the initial URL is set to https://maps.google.com

The problem can be illustrated by clicking the compass icon in the bottom right ("show my current location"). The slot attempts to grant permission as follows:

void WebPage::handleFeaturePermissionRequested(const QUrl &securityOrigin, QWebEnginePage::Feature feature)
{
    // hgroover: make this browser promiscuous - share location with any website
    qDebug() << "Granting request" << feature << "for" << securityOrigin;
    // This seems it should allow the request to complete
    setFeaturePermission( securityOrigin, feature, QWebEnginePage::PermissionGrantedByUser);
}

The slot is invoked as expected and the setFeaturePermission() call is completed.

The user is presented with 3 successive prompts:

“simplebrowser” would like to use your current location. [Don't allow] [Allow]

After clicking allow three times, the location request goes through.

The apparently defective behavior is why I am prompted three times?

Desired behavior would be to handle this prompt myself and use setFeaturePermission() to communicate the results of the user interaction. However, it seems that setFeaturePermission() only allows the browser to prompt for permission. Running the unmodified simplebrowser example, clicking on current location does nothing.