A not so clear behaviour for Makefiles including other makefiles

[Cristian Zoicas]

Hello all

I've discovered that the  makefiles including other makefiles
are read two times when the included makefiles must be remade
even if the including makefile is not remade.

It means that any

$(warning ... ) or __d := $(shell ... )

function  calls are executed to times if they do not apear as
commands in rules.

I would like to know if this behaviour is by design.

Thank you in advance
Cristian Zoicas