[mkgmap-dev] Routing problem on Edge 800

I have recently noticed a problem when following routes or tracks on my 800, with turn guidance turned on. Sometimes, the calculated route diverges from the gpx track and road, and makes a straight line to somewhere further on. The attached screenshot shows an example. I build my own maps, and noticed this problem with mkgmap-r2643. When I build a map with mkgmap-r2585 (the most recent older version I have), I do not see this problem. If someone can point me at any intermediate versions (I don't build mkgmap from source), then I can try and narrow down when the problem first occurs. Steve