Update only if it makes sense.

oi-sensor/oi-sensor.py

@@ -161,6 +161,7 @@ async def main():
                     print("\tDetected area (px)=%.2f, result=%d, shape changes=%d" %(area, result, shape_change_counter))
 
                     # update list for last X results (FILO)
+                    if current_shape != result:
                         result_stack.append(result)
                         current_shape = result
                         shape_change_counter += 1
@@ -173,6 +174,7 @@ async def main():
             if not contour_detected:
                 # no countours actually detected thus update OPC UA server's node attribute
                 result = 0.0
+                if current_shape != result:
                     result_stack.append(result)
                     shape_change_counter += 1
                     await myvar.write_value(result)