Toolbar Items not clearing on carouselPage

i am using masterdetail & a carouselPage named MycarouselPage(user can navigate to this page through masterdetail menu) & toolbar items are added on child pages.
i am trying to change toolbar items while switching MycarouselPage's child pages. If i navigate to MycarouselPage through pushAsync it works.

But if i assign MycarouselPage as navigationPage to detail page then toolbaritems don't switch(tried clearing and readding them as well but no Success).

Attached a sample project
i checked it with forms 1.2.3.6257, latest Stable version 1.4.3.6376 and pre release but not working.