[qtbase] Ignore irrelevant session state change events. Contributes t…

…o JB#33794

The next stateChanged() may already be queued by the time we have received
closed() signal and cleared the session reference. Sometimes that was
resulting in QNetworkAccessManager getting stuck in NotAccessible state.

src/network/access/qnetworkaccessmanager.cpp

@@ -1566,6 +1566,13 @@ void QNetworkAccessManagerPrivate::_q_networkSessionStateChanged(QNetworkSession
 {
     Q_Q(QNetworkAccessManager);
 
+    if (!networkSessionStrongRef) {
+        // The next stateChanged() may already be queued by the time we have
+        // received closed() signal and cleared the session reference.
+        lastSessionState = QNetworkSession::Invalid;
+        return;
+    }
+
     //Do not emit the networkSessionConnected signal here, except for roaming -> connected
     //transition, otherwise it is emitted twice in a row when opening a connection.
     if (state == QNetworkSession::Connected && lastSessionState == QNetworkSession::Roaming)