Lines 66 - 74 amended. Causes "[User Warning] popCurrent called on ModelAsController controller, but it wasn't at the top of the stack" and "[User Warning] Couldn't set response type to 404 because of output on line 101 of /Users/lawrence/Devsites/abelhomes/framework/dev/DebugView.php" on sites that are in dev mode.

RequestHandler.php

<?php

    /**
     * Handles URL requests.
	 *
	 *  - ViewableData::handleRequest() iterates through each rule in {@link self::$url_handlers}.
	 *  - If the rule matches, the named method will be called.
	 *  - If there is still more URL to be processed, then handleRequest() 
	 *    is called on the object that that method returns.
	 *
	 * Once all of the URL has been processed, the final result is returned.  
	 * However, if the final result is an array, this
	 * array is interpreted as being additional template data to customise the 
	 * 2nd to last result with, rather than an object
	 * in its own right.  This is most frequently used when a Controller's 
	 * action will return an array of data with which to
	 * customise the controller.
	 * 
	 * @param $request The {@link SS_HTTPRequest} object that is reponsible for distributing URL parsing
	 * @uses SS_HTTPRequest
	 * @uses SS_HTTPRequest->match()
	 * @return SS_HTTPResponse|RequestHandler|string|array
	 */
	public function handleRequest(SS_HTTPRequest $request, DataModel $model) {
		// $handlerClass is used to step up the class hierarchy to implement url_handlers inheritance
		$handlerClass = ($this->class) ? $this->class : get_class($this);
	
		if($this->brokenOnConstruct) {
			user_error("parent::__construct() needs to be called on {$handlerClass}::__construct()", E_USER_WARNING);
		}
	
		$this->request = $request;
		$this->setDataModel($model);

		$match = $this->findAction($request);

		// If nothing matches, return this object
		if (!$match) return $this;

		// Start to find what action to call. Start by using what findAction returned
		$action = $match['action'];

		// We used to put "handleAction" as the action on controllers, but (a) this could only be called when
		// you had $Action in your rule, and (b) RequestHandler didn't have one. $Action is better
		if ($action == 'handleAction') {
			Deprecation::notice('3.2.0', 'Calling handleAction directly is deprecated - use $Action instead');
			$action = '$Action';
		}

		// Actions can reference URL parameters, eg, '$Action/$ID/$OtherID' => '$Action',
		if($action[0] == '$') {
			$action = str_replace("-", "_", $request->latestParam(substr($action,1)));
		}

		if(!$action) {
			if(isset($_REQUEST['debug_request'])) {
				Debug::message("Action not set; using default action method name 'index'");
			}
			$action = "index";
		} else if(!is_string($action)) {
			user_error("Non-string method name: " . var_export($action, true), E_USER_ERROR);
		}

		$className = get_class($this);

		if(!$this->hasAction($action)) {
			// return new SS_HTTPResponse("Action '$action' isn't available on class $className.", 404);
			return $this->httpError(404, "Action '$action' isn't available on class $classname.");
		}

		if(!$this->checkAccessAction($action) || in_array(strtolower($action), array('run', 'init'))) {
			// return new SS_HTTPResponse("Action '$action' isn't allowed on class $className.", 403);
			return $this->httpError(403, "Action '$action' isn't allowed on class $classname.");
		}

		try {
			$result = $this->handleAction($request, $action);
		}
		catch (SS_HTTPResponse_Exception $e) {
			return $e->getResponse();
		}
		catch(PermissionFailureException $e) {
			$result = Security::permissionFailure(null, $e->getMessage());
		}

		if($result instanceof SS_HTTPResponse && $result->isError()) {
			if(isset($_REQUEST['debug_request'])) Debug::message("Rule resulted in HTTP error; breaking");
			return $result;
		}

		// If we return a RequestHandler, call handleRequest() on that, even if there is no more URL to
		// parse. It might have its own handler. However, we only do this if we haven't just parsed an
		// empty rule ourselves, to prevent infinite loops. Also prevent further handling of controller
		// actions which return themselves to avoid infinite loops.
		$matchedRuleWasEmpty = $request->isEmptyPattern($match['rule']);
		$resultIsRequestHandler = is_object($result) && $result instanceof RequestHandler;
		
		if($this !== $result && !$matchedRuleWasEmpty && $resultIsRequestHandler) {
			$returnValue = $result->handleRequest($request, $model);

			// Array results can be used to handle
			if(is_array($returnValue)) $returnValue = $this->customise($returnValue);

			return $returnValue;

		// If we return some other data, and all the URL is parsed, then return that
		} else if($request->allParsed()) {
			return $result;

		// But if we have more content on the URL and we don't know what to do with it, return an error.
		} else {
			return $this->httpError(404, "I can't handle sub-URLs of a $this->class object.");
		}

		return $this;
	}