WebEngine FaviconManager ASSERTs when quickly calling setHtml

Running some tests for a different bug, I came across this:

When setHtml is called often, in short intervals, providing a second parameter (const QUrl& baseUrl, I used QUrl("http://foo.bar")), FaviconManagerPrivate::storeIcon can ASSERT in Line 144

    // Icon download has been interrupted
    if (m_inProgressRequests.isEmpty())
        return;

    Q_ASSERT(m_inProgressRequests.contains(id));  <---- HERE

In the debugger I have seen that m_inProgressRequests does contain the URL, just under a different id. Probably a race condition.