silverstripe-framework/admin/code/LeftAndMain_HTTPResponse.php

<?php

namespace SilverStripe\Admin;

use SilverStripe\Control\SS_HTTPResponse;

/**
 * Allow overriding finished state for faux redirects.
 */
class LeftAndMain_HTTPResponse extends SS_HTTPResponse
{

	protected $isFinished = false;

	public function isFinished()
	{
		return (parent::isFinished() || $this->isFinished);
	}

	public function setIsFinished($bool)
	{
		$this->isFinished = $bool;
	}

}