Compilation error on openfl3 branch

I’m using HaxeFlixel, and since it doesn’t yet fully work on OpenFl4, I want to use openfl3 branch which has more bug fixes than 3.6.1 stable version.
But when I compile my project on neko or windows I get this error:

D:/build/HaxeToolkit/haxe/lib/openfl/git/openfl/_internal/renderer/opengl/GLRenderer.hx:49: characters 8-46 : 
Type name openfl._internal.renderer.opengl.utils.GLBlendMode is redefined from module openfl._internal.renderer.opengl.utils.GLBlendModeManager

Any clue?