Diag: getCurrentMachineState: return previousState ...

... if diag is running.
This method is currently not used, but maybe in future it could be
usefull to read current state.

src/ATBAPP/DeviceControllerDiag.cpp

@@ -98,6 +98,9 @@ bool DeviceControllerDiag::isOperatingState()
 
 QSet<DCMachineEvent> DeviceControllerDiag::getCurrentMachineState()
 {
+    // ensure that currentMachineEventSet is delivered here
+    if (this->isRequestRunning) return this->previousMachineEventSet;
+
     return this->machineEventSet;
 }