Fix overzealous breakSegments()

We cannot break segements that are merely close or on endpoints, so we
filter these prior to the break routine.  Failing to do this was
overloading our undo stack with bogus values

Fixes https://gitlab.com/kicad/code/kicad/issues/7553

Fixes https://gitlab.com/kicad/code/kicad/issues/7557

Fixes https://gitlab.com/kicad/code/kicad/issues/7554

eeschema/bus-wire-junction.cpp

@@ -329,7 +329,15 @@ bool SCH_EDIT_FRAME::BreakSegments( const wxPoint& aPoint, SCH_SCREEN* aScreen )
     for( auto item : aScreen->Items().Overlapping( SCH_LINE_T, aPoint ) )
     {
         if( item->IsType( wiresAndBuses ) )
-            wires.push_back( static_cast<SCH_LINE*>( item ) );
+        {
+            SCH_LINE* wire = static_cast<SCH_LINE*>( item );
+
+            if( IsPointOnSegment( wire->GetStartPoint(), wire->GetEndPoint(), aPoint )
+                                && !wire->IsEndPoint( aPoint ) )
+            {
+                wires.push_back( wire );
+            }
+        }
     }
 
     for( auto wire : wires )

eeschema/schematic_undo_redo.cpp

@@ -97,8 +97,8 @@
 
 void SCH_EDIT_FRAME::StartNewUndo()
 {
-	PICKED_ITEMS_LIST* blank = new PICKED_ITEMS_LIST();
+    PICKED_ITEMS_LIST* blank = new PICKED_ITEMS_LIST();
-	PushCommandToUndoList( blank );
+    PushCommandToUndoList( blank );
 }
 
 
@@ -114,16 +114,16 @@ void SCH_EDIT_FRAME::SaveCopyInUndoList( SCH_SCREEN*    aScreen,
     // Connectivity may change
     aItem->SetConnectivityDirty();
 
-	PICKED_ITEMS_LIST* lastUndo = PopCommandFromUndoList();
+    PICKED_ITEMS_LIST* lastUndo = PopCommandFromUndoList();
 
-	// If the last stack was empty, use that one instead of creating a new stack
+    // If the last stack was empty, use that one instead of creating a new stack
-	if( lastUndo )
+    if( lastUndo )
-	{
+    {
-		if( aAppend || !lastUndo->GetCount() )
+        if( aAppend || !lastUndo->GetCount() )
-			commandToUndo = lastUndo;
+            commandToUndo = lastUndo;
-		else
+        else
-			PushCommandToUndoList( lastUndo );
+            PushCommandToUndoList( lastUndo );
-	}
+    }
 
     if( !commandToUndo )
     {
@@ -175,8 +175,16 @@ void SCH_EDIT_FRAME::SaveCopyInUndoList( const PICKED_ITEMS_LIST& aItemsList,
     if( !aItemsList.GetCount() )
         return;
 
-    if( aAppend )
+    PICKED_ITEMS_LIST* lastUndo = PopCommandFromUndoList();
-        commandToUndo = PopCommandFromUndoList();
+
+    // If the last stack was empty, use that one instead of creating a new stack
+    if( lastUndo )
+    {
+        if( aAppend || !lastUndo->GetCount() )
+            commandToUndo = lastUndo;
+        else
+            PushCommandToUndoList( lastUndo );
+    }
 
     if( !commandToUndo )
         commandToUndo = new PICKED_ITEMS_LIST();
@@ -267,7 +275,7 @@ void SCH_EDIT_FRAME::PutDataInPreviousState( PICKED_ITEMS_LIST* aList )
 
         if( status == UNDO_REDO::NOP )
         {
-        	continue;
+            continue;
         }
         if( status == UNDO_REDO::NEWITEM )
         {
@@ -343,8 +351,12 @@ void SCH_EDIT_FRAME::RollbackSchematicFromUndo()
     PICKED_ITEMS_LIST* undo = PopCommandFromUndoList();
 
     // Skip empty frames
-    while( undo && undo->GetCount() == 1 && undo->GetPickedItemStatus( 0 ) == UNDO_REDO::NOP )
+    while( undo && ( !undo->GetCount()
-    	undo = PopCommandFromUndoList();
+            || ( undo->GetCount() == 1 && undo->GetPickedItemStatus( 0 ) == UNDO_REDO::NOP ) ) )
+    {
+        delete undo;
+        undo = PopCommandFromUndoList();
+    }
 
     if( undo )
     {

eeschema/tools/sch_edit_tool.cpp

@@ -66,7 +66,6 @@
 #include <dialogs/dialog_edit_label.h>
 #include <core/kicad_algo.h>
 
-#include <limits>
 
 class SYMBOL_UNIT_MENU : public ACTION_MENU
 {
@@ -1692,21 +1691,21 @@ int SCH_EDIT_TOOL::BreakWire( const TOOL_EVENT& aEvent )
 
     for( auto& item : selection )
     {
-    	if( SCH_LINE* line = dyn_cast<SCH_LINE*>( item ) )
+        if( SCH_LINE* line = dyn_cast<SCH_LINE*>( item ) )
-		{
+        {
-    		if( !line->IsEndPoint( cursorPos ) )
+            if( !line->IsEndPoint( cursorPos ) )
-    		lines.push_back( line );
+            lines.push_back( line );
-		}
+        }
     }
 
     m_selectionTool->ClearSelection();
-	m_frame->StartNewUndo();
+    m_frame->StartNewUndo();
 
-	for( SCH_LINE* line : lines )
+    for( SCH_LINE* line : lines )
-		m_frame->BreakSegment( line,  cursorPos );
+        m_frame->BreakSegment( line,  cursorPos );
 
-	if( !lines.empty() )
+    if( !lines.empty() )
-	{
+    {
         if( m_frame->GetScreen()->IsJunctionNeeded( cursorPos, true ) )
             m_frame->AddJunction( m_frame->GetScreen(), cursorPos, true, false );