Let's say I have a package installed with the USE flag example enabled; now because the example feature is broken, we force disable it in package.use.mask. When doing a `emerge -uDN @world` or so, this causes the USE flag to change; it would be nice if we would then show the mask reason for the USE flag (like with the package masks) such that the user knows why it is broken; otherwise the user would be surprised and ask about it on the forums, bugzilla or even upstream. So, can we show package.use.mask's reason when it causes a change in USE flag? This is for the same reason as to why we currently show package.mask entries. There is also the occasion where the user (or selected profile) explicitly sets the USE flags, where it asks the user to make a change to package.use; we could show it then as well. Please also note that this question might apply to other profiles' files too, but I haven't looked into them yet (as they are not masks). Thank you very much in advance.
