pcbnew: Don't merge zones with different params

Zones can be explicitly merged even if they do not have the same
parameters.  Automatic merging should only occur when all of the zone
parameters are exactly identical to allow for area-specific zone
parameters.

Fixes: lp:1695761
* https://bugs.launchpad.net/kicad/+bug/1695761

pcbnew/zones_test_and_combine_areas.cpp

@@ -196,6 +196,36 @@ bool BOARD::TestAreaIntersections( ZONE_CONTAINER* area_to_test )
             if( area_to_test->GetDoNotAllowVias() != area2->GetDoNotAllowVias() )
                 continue;
         }
+        // Filled zone specific tests
+        else
+        {
+            if( area_to_test->GetClearance() != area2->GetClearance() )
+                continue;
+
+            if( area_to_test->GetThermalReliefGap() != area2->GetThermalReliefGap() )
+                continue;
+
+            if( area_to_test->GetThermalReliefCopperBridge() != area2->GetThermalReliefCopperBridge() )
+                continue;
+
+            if( area_to_test->GetArcSegmentCount() != area2->GetArcSegmentCount() )
+                continue;
+
+            if( area_to_test->GetZoneClearance() != area2->GetZoneClearance() )
+                continue;
+
+            if( area_to_test->GetPadConnection() != area2->GetPadConnection() )
+                continue;
+
+            if( area_to_test->GetMinThickness() != area2->GetMinThickness() )
+                continue;
+
+            if( area_to_test->GetCornerSmoothingType() != area2->GetCornerSmoothingType() )
+                continue;
+
+            if( area_to_test->GetCornerRadius() != area2->GetCornerRadius() )
+                continue;
+        }
 
         if( TestAreaIntersection( area_to_test, area2 ) )
             return true;