Reverse shown-source logic so we report if it's the netclass width.

(whether or not it's *also* the previous track width).

pcbnew/router/router_tool.cpp

@@ -716,8 +716,9 @@ void ROUTER_TOOL::updateSizesAfterLayerSwitch( PCB_LAYER_ID targetLayer )
         {
             int width = sizes.TrackWidth();
 
-            // Only change the size if we're explicitly using the net class, or we're out of range for our
-            // new constraints. Otherwise, just leave the track width alone so we don't change for no reason.
+            // Only change the size if we're explicitly using the net class, or we're out of range
+            // for our new constraints. Otherwise, just leave the track width alone so we don't
+            // change for no reason.
             if( bds.UseNetClassTrack()
                     || ( width < bds.m_TrackMinWidth )
                     || ( width < constraint.m_Value.Min() )
@@ -726,12 +727,12 @@ void ROUTER_TOOL::updateSizesAfterLayerSwitch( PCB_LAYER_ID targetLayer )
                 sizes.SetTrackWidth( std::max( bds.m_TrackMinWidth, constraint.m_Value.Opt() ) );
             }
 
-            if( sizes.TrackWidth() == width )
-                sizes.SetWidthSource( _( "existing track" ) );
+            if( sizes.TrackWidth() == constraint.m_Value.Opt() )
+                sizes.SetWidthSource( constraint.GetName() );
             else if( sizes.TrackWidth() == bds.m_TrackMinWidth )
                 sizes.SetWidthSource( _( "board minimum track width" ) );
             else
-                sizes.SetWidthSource( constraint.GetName() );
+                sizes.SetWidthSource( _( "existing track" ) );
         }
     }