From 6b75f589e94315f7c0ee0c11906ef5f4004ade23 Mon Sep 17 00:00:00 2001
From: Seth Hillbrand <hillbrand@ucdavis.edu>
Date: Thu, 10 Jan 2019 06:17:37 -0800
Subject: [PATCH] pcbnew: Do not remove islands from no-net zones

No net zones, by definition, do not connect to any other element.
Therefore, the entire net is an island and should not be removed by the
knockout section

Fixes: lp:1811239
* https://bugs.launchpad.net/kicad/+bug/1811239
---
 pcbnew/zone_filler.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/pcbnew/zone_filler.cpp b/pcbnew/zone_filler.cpp
index 31f9ebf351..689650b63c 100644
--- a/pcbnew/zone_filler.cpp
+++ b/pcbnew/zone_filler.cpp
@@ -191,6 +191,10 @@ bool ZONE_FILLER::Fill( std::vector<ZONE_CONTAINER*> aZones, bool aCheck )
 
     for( auto& zone : toFill )
     {
+        // Non-net zones do not have islands by definition
+        if( zone.m_zone->GetNetCode() <= 0 )
+            continue;
+
         std::sort( zone.m_islands.begin(), zone.m_islands.end(), std::greater<int>() );
         SHAPE_POLY_SET poly = zone.m_zone->GetFilledPolysList();