Bug 89020 [Undo] Operation throws assertion failure if undo limit is set to 0
I20050324-0800 Unfortunately existing clients of text's undo manager were allowed to set any number without failing. This is no longer possible: an assertion failure occurrs if the limit is smaller than 1. I will add code on my side that will handle the negative numbers but the operation history must allow 0.
bundles/org.eclipse.core.commands/src/org/eclipse/core/commands/operations/DefaultOperationHistory.java
* 
	 * @param monitor
	 * @param operation
	 */
	protected IStatus doRedo(IProgressMonitor monitor, IAdaptable info, IUndoableOperation operation,
			boolean flushOnError) throws ExecutionException{
		IStatus status = getRedoApproval(operation, info);
		if (status.isOK()) {
			notifyAboutToRedo(operation);
			try {
				status = operation.redo(monitor, info);
			} catch (OperationCanceledException e) {
				status = Status.CANCEL_STATUS;
			} catch (ExecutionException e) {
				notifyNotOK(operation);
				if (DEBUG_OPERATION_HISTORY_UNEXPECTED) {
					System.out.print("OPERATIONHISTORY >>> ExecutionException while redoing ");  
					System.out.print(operation);
					System.out.println();
				}
				throw e;
			} catch (Exception e) {
				notifyNotOK(operation);
				if (DEBUG_OPERATION_HISTORY_UNEXPECTED) {
					System.out.print("OPERATIONHISTORY >>> Exception while redoing ");  
					System.out.print(operation);
					System.out.println();
				}
				throw new ExecutionException(
						"While redoing the operation, an exception occurred", e);