why make not give message about target being up-to-date in this VPATH situation?

[Britton Kerin]

Given this Makefile:

VPATH = a_subdir

foo: some_prereq
        touch $@

bar: some_prereq
        touch $(VPATH)/$@

$(VPATH)/baz: some_prereq
        touch $@

Rebuilding an already-up-to-date $(VPATH)/baz using 'make baz' doesn't
give the usual "is up to date" message, even though the recipe is not
executed.  It does give this message for the bar target (and for the
non-VPATH normal case foo).  Why?

Behavior:

$ mkdir a_subdir
$ touch some_prereq
$ make foo
touch foo
$ make bar
touch a_subdir/bar
$ make bar
make: 'a_subdir/bar' is up to date.
$ make baz
touch a_subdir/baz
$ make baz
$ touch some_prereq
$ make baz
touch a_subdir/baz
$ make baz
$ make a_subdir/baz
make: 'a_subdir/baz' is up to date.
$ make --version
GNU Make 4.2
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License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
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