My wild guess is that has is not given any magic (like compile-time action) -- as Moose design seems not to favour source filters (but who favours source filters anyway?). That way, what happens is that "test" does not has "x" when the "new" runs. But this is just a hunch as I have not found the time to play with Moose yet.

Update: Note that disparaged behaviour is not noticed when classes are confined to their own files and used (when everything at the package source would run at compile-time from the perspective of the caller of use).