Scheduled stops

I just discovered today that I'm probably not allowed to use the 72h Visa-free entry, because my flight to and from Bejing is stopping in Nanjing for 45min (for refueling, and so on).
Therefor it seems that the flight will not be seen as direct flight from/to a foreign country, even if the I don't change planes and the flight-number remains the same.
Is that right?