Reproduction case for Flixel BitmapData glitch with stamp()

Main.hx

package;

import flash.display.Sprite;
import flash.display.StageAlign;
import flash.display.StageScaleMode;
import flash.events.Event;
import flash.Lib;
import flixel.FlxGame;
import flixel.FlxState;

class Main extends Sprite 
{
	var gameWidth:Int = 320; // Width of the game in pixels (might be less / more in actual pixels depending on your zoom).
	var gameHeight:Int = 240; // Height of the game in pixels (might be less / more in actual pixels depending on your zoom).
	var initialState:Class<FlxState> = MenuState; // The FlxState the game starts with.
	var zoom:Float = -1; // If -1, zoom is automatically calculated to fit the window dimensions.
	var framerate:Int = 60; // How many frames per second the game should run at.
	var skipSplash:Bool = false; // Whether to skip the flixel splash screen that appears in release mode.
	var startFullscreen:Bool = false; // Whether to start the game in fullscreen on desktop targets
	
	// You can pretty much ignore everything from here on - your code should go in your states.
	
	public static function main():Void
	{	
		Lib.current.addChild(new Main());
	}
	
	public function new() 
	{
		super();
		
		if (stage != null) 
		{
			init();
		}
		else 
		{
			addEventListener(Event.ADDED_TO_STAGE, init);
		}
	}
	
	private function init(?E:Event):Void 
	{
		if (hasEventListener(Event.ADDED_TO_STAGE))
		{
			removeEventListener(Event.ADDED_TO_STAGE, init);
		}
		
		setupGame();
	}
	
	private function setupGame():Void
	{
		var stageWidth:Int = Lib.current.stage.stageWidth;
		var stageHeight:Int = Lib.current.stage.stageHeight;

		if (zoom == -1)
		{
			var ratioX:Float = stageWidth / gameWidth;
			var ratioY:Float = stageHeight / gameHeight;
			zoom = Math.min(ratioX, ratioY);
			gameWidth = Math.ceil(stageWidth / zoom);
			gameHeight = Math.ceil(stageHeight / zoom);
		}

		addChild(new FlxGame(gameWidth, gameHeight, initialState, zoom, framerate, framerate, skipSplash, startFullscreen));
	}
}

MenuState.hx

package;

import flixel.addons.ui.FlxUIButton;
import flixel.addons.ui.FlxUICheckBox;
import flixel.addons.ui.FlxUICursor;
import flixel.addons.ui.FlxUIState;
import flixel.addons.ui.FlxUIText;
import flixel.addons.ui.interfaces.IFlxUIWidget;
import flixel.FlxSprite;
import flixel.util.FlxColor;
import openfl.Assets;
import openfl.geom.Rectangle;

/**
 * A FlxState which can be used for the game's menu.
 */
class MenuState extends FlxUIState
{
	/**
	 * Function that is called up when to state is created to set it up. 
	 */
	override public function create():Void
	{
		super.create();
		
		var test = new FlxSprite();
		
		test.makeGraphic(256, 100, FlxColor.RED);
		test.graphic.bitmap.fillRect(new Rectangle(0, 50, 256, 50), FlxColor.BLUE);
		
		var fs:FlxSprite = new FlxSprite(0, 0, "assets/openfl.png");
		
		test.stamp(fs);
		add(test);
	}
}

Project.xml

<?xml version="1.0" encoding="utf-8"?>
<project>
	<!------------------------------APPLICATION SETTINGS---------------------------->
	
	<app title="Cursor" file="Cursor" main="Main" version="0.0.1" company="HaxeFlixel" />
	
	<!--The flixel preloader is not accurate in Chrome. You can use it regularly if you embed the swf into a html file
	<!--or you can set the actual size of your file manually at "FlxPreloaderBase-onUpdate-bytesTotal"!-->
	<app preloader="flixel.system.FlxPreloader" />
	
	<!--Minimum without FLX_NO_GAMEPAD: 11.8, without FLX_NO_NATIVE_CURSOR: 11.2 -->
	<set name="SWF_VERSION" value="11.8" />
	
	<!--------------------------------WINDOW SETTINGS------------------------------->
	
	<!--These window settings apply to all targets-->
	<window width="640" height="480" fps="60" background="#000000" hardware="true" vsync="true" />
	
	<!--Web-specific-->
	<window if="web" orientation="portrait"  />
	
	<!--Desktop-specific-->
	<window if="desktop" orientation="landscape" fullscreen="false" resizable="true" />
	
	<!--Mobile-specific-->
	<window if="mobile" orientation="landscape" fullscreen="true" width="0" height="0" />
	
	<!--------------------------------PATHS SETTINGS-------------------------------->
	
	<set name="BUILD_DIR" value="export" />
	<classpath name="source" />
	<assets path="assets" />
	
	<!--------------------------------LIBRARIES------------------------------------->

	<haxelib name="flixel"/>
	
	<!--In case you want to use the addons package-->
	<!--haxelib name="flixel-addons" /-->
	
	<!--In case you want to use the ui package-->
	<haxelib name="flixel-ui"/>
	
	<!--In case you want to use nape with flixel-->
	<!--haxelib name="nape" /-->
	
	<!--------------------------------HAXEDEFINES----------------------------------->
	
	<!--Enable the Flixel core recording system-->
	<!--haxedef name="FLX_RECORD" /-->
	
	<!--Disable the right and middle mouse buttons-->
	<!--haxedef name="FLX_NO_MOUSE_ADVANCED" /-->
	
	<!--Disable the Native cursor api for Flash target-->
	<!--haxedef name="FLX_NO_NATIVE_CURSOR" /-->
	
	<!--Optimise inputs, be careful you will get null errors if you don't use conditionals in your game-->
	<haxedef name="FLX_NO_MOUSE" if="mobile" />
	<haxedef name="FLX_NO_KEYBOARD" if="mobile" />
	<haxedef name="FLX_NO_TOUCH" if="desktop" />
	<!--haxedef name="FLX_NO_GAMEPAD" /-->
	
	<!--Disable the Flixel core sound tray-->
	<!--haxedef name="FLX_NO_SOUND_TRAY" /-->
	
	<!--Disable the Flixel sound management code-->
	<!--haxedef name="FLX_NO_SOUND_SYSTEM" /-->
	
	<!--Disable the Flixel core focus lost screen-->
	<!--haxedef name="FLX_NO_FOCUS_LOST_SCREEN" /-->
	
	<!--Disable the Flixel core debugger. Automatically gets set whenever you compile in release mode!-->
	<haxedef name="FLX_NO_DEBUG" unless="debug" />
	
	<!--Enable this for Nape release builds for a serious peformance improvement-->
	<haxedef name="NAPE_RELEASE_BUILD" unless="debug" />
	
	<!--------------------------------CUSTOM---------------------------------------->
	
	<!--Place custom nodes like icons here (higher priority to override the HaxeFlixel icon)-->
</project>