itojun@iijlab.net writes:
> 	Now I see... it was required to perform "make cleandir" (or don't
> 	set UPDATE) with the change, otherwise "realdepend" rule (bsd.dep.mk)
> 	will not notice that .depend is obsolete due to change caused by .PATH.
> 	Thanks.

Yeah, I've done this mistake myself a number of times. :-)

> 	I understand I was wrong that setting UPDATE=1, however, I think
> 	"make UPDATE=1 build" case should somehow be improved to catch this
> 	case.  Is it possible to write a make rule to add the following:
> 
> >>.depend: (the makefiles we use for the bulid, including Makefile.frag)

That's done in the particular Makefile, so it might not be so easy.
Adding a dependency on Makefile should be trivial, however.

/assar