Special case for very-short tracks was killing both-ends-in-a-zone.

(And doing so randomly as if the closer endpoint to the zone center
was the one without a pad then it would get marked as good, while if
it was the other way around we'd notch 2 connections for the pad end
and none for the other end.)

Fixes https://gitlab.com/kicad/code/kicad/issues/13420

pcbnew/connectivity/connectivity_data.cpp

@@ -2,7 +2,7 @@
  * This program source code file is part of KICAD, a free EDA CAD application.
  *
  * Copyright (C) 2017 CERN
- * Copyright (C) 2018-2022 KiCad Developers, see AUTHORS.txt for contributors.
+ * Copyright (C) 2018-2023 KiCad Developers, see AUTHORS.txt for contributors.
  * @author Tomasz Wlostowski <tomasz.wlostowski@cern.ch>
  *
  * This program is free software; you can redistribute it and/or
@@ -755,6 +755,12 @@ bool CONNECTIVITY_DATA::TestTrackEndpointDangling( PCB_TRACK* aTrack, VECTOR2I*
 
             if( hitStart && hitEnd )
             {
+                if( zone )
+                {
+                    // Both start and end in a zone: track may be redundant, but it's not dangling
+                    return false;
+                }
+
                 if( getMinDist( item, aTrack->GetStart() ) < getMinDist( item, aTrack->GetEnd() ) )
                     start_count++;
                 else