Bug 123316 [Undo] - API BEHAVIOR - should always place a successfully undone/redone op on the redo/undo history
bundles/org.eclipse.core.commands/src/org/eclipse/core/commands/operations/DefaultOperationHistory.java
if (DEBUG_OPERATION_HISTORY_NOTIFICATION) {
			Tracing.printTrace("OPERATIONHISTORY", "REDONE " + operation); 
		}
		notifyListeners(new OperationHistoryEvent(OperationHistoryEvent.REDONE,
				this, operation));
	}
	/*
	 * Notify listeners that an operation has been removed from the history.
	 */
	private void notifyRemoved(IUndoableOperation operation) {
		if (DEBUG_OPERATION_HISTORY_NOTIFICATION) {
			Tracing.printTrace("OPERATIONHISTORY", "OPERATION_REMOVED " 
					+ operation);
		}
		notifyListeners(new OperationHistoryEvent(
				OperationHistoryEvent.OPERATION_REMOVED, this, operation));
	}
	/*
	 * Notify listeners that an operation has been undone.
	 */
	private void notifyUndone(IUndoableOperation operation) {
		if (DEBUG_OPERATION_HISTORY_NOTIFICATION) {
			Tracing.printTrace("OPERATIONHISTORY", "UNDONE " + operation); 
		}
		notifyListeners(new OperationHistoryEvent(OperationHistoryEvent.UNDONE,
				this, operation));
	}
	/*
	 * Notify listeners that an operation has been undone.
	 */