Make sure pads with no net get assigned Default netclass on board open.

Fixes https://gitlab.com/kicad/code/kicad/-/issues/15562

pcbnew/plugins/kicad/pcb_parser.cpp

@@ -4189,6 +4189,7 @@ PAD* PCB_PARSER::parsePAD( FOOTPRINT* aParent )
 
     VECTOR2I sz;
     VECTOR2I pt;
+    bool     foundNet = false;
 
     std::unique_ptr<PAD> pad = std::make_unique<PAD>( aParent );
 
@@ -4395,6 +4396,8 @@ PAD* PCB_PARSER::parsePAD( FOOTPRINT* aParent )
         }
 
         case T_net:
+            foundNet = true;
+
             if( ! pad->SetNetCode( getNetCode( parseInt( "net number" ) ), /* aNoAssert */ true ) )
             {
                 wxLogError( _( "Invalid net ID in\nfile: %s\nline: %d offset: %d" ),
@@ -4694,6 +4697,12 @@ PAD* PCB_PARSER::parsePAD( FOOTPRINT* aParent )
         }
     }
 
+    if( !foundNet )
+    {
+        // Make sure default netclass is correctly assigned to pads that don't define a net.
+        pad->SetNetCode( 0, /* aNoAssert */ true );
+    }
+
     if( !pad->CanHaveNumber() )
     {
         // At some point it was possible to assign a number to aperture pads so we need to clean

qa/data/pcbnew/issue7567.kicad_pro

@@ -409,7 +409,7 @@
     "classes": [
       {
         "bus_width": 12,
-        "clearance": 0.2032,
+        "clearance": 0.1778,
         "diff_pair_gap": 0.25,
         "diff_pair_via_gap": 0.25,
         "diff_pair_width": 0.2,