PNS router doesn't take into account copper layers which have been removed from a PTH. (lp:#1618230)
Original report created by Simon Richter (sjr)
When a via or thru-hole pad is placed, the inner layers will also receive
annular rings, even if there are no connections there. That makes it more
difficult to route signals between pins.
Ideally, only clearance from the drill hole would be required on these
layers.
Original tags: cern pcbnew pns