nearestneighborlinker: add an early exit test
nearestneighborlinker: add an early exit test

Thanks to Dave Cave for noticing.
Signed-off-by: Jean-Yves Tinevez <17c1793fcc6179ec3ae6319887e209161427f317@gmail.com>

tinevez/jyt-matlab,tinevez/jyt-matlab,tinevez/jyt-matlab,tinevez/jyt-matlab,tinevez/jyt-matlab