xsfbs bug: configure not up to date after running debian/rules build

[Sven Joachim <svenjoac@gmx.de>]

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Hi,

while preparing the xserver-xorg-video-nouveau package I noticed that
debuild remade the build target twice which is annoying.  I think this
can be traced down to a bug in xfsbs.  My debian/rules targets look
innocent enough, and they seem like what it recommended by xsfbs'
README.source:

[...]
build: build-stamp
build-stamp: configure
	dh_testdir
	test -d obj-$(DEB_BUILD_GNU_TYPE) || mkdir obj-$(DEB_BUILD_GNU_TYPE)
	cd obj-$(DEB_BUILD_GNU_TYPE) && \
	../configure --prefix=/usr --mandir=\$${prefix}/share/man \
	             --infodir=\$${prefix}/share/info $(confflags) \
	             CFLAGS="$(CFLAGS)" CPPFLAGS="$(CPPFLAGS)"
	cd obj-$(DEB_BUILD_GNU_TYPE) && $(MAKE)
	touch $@

configure: $(STAMP_DIR)/patch
	dh_testdir
	autoreconf -vfi

install: build
	dh_testdir
[...]

Running "debian/rules build" and then debugging the issue with
"debian/rules -n -d configure" prints this:

[...]
Updating goal targets....
Considering target file `configure'.
  Considering target file `stampdir/patch'.
    Considering target file `stampdir/prepare'.
      Considering target file `stampdir/log'.
        Considering target file `stampdir/stampdir'.
         Finished prerequisites of target file `stampdir/stampdir'.
        No need to remake target `stampdir/stampdir'.
       Finished prerequisites of target file `stampdir/log'.
       Prerequisite `stampdir/stampdir' is older than target `stampdir/log'.
      No need to remake target `stampdir/log'.
      Considering target file `stampdir/genscripts'.
        Pruning file `stampdir/stampdir'.
       Finished prerequisites of target file `stampdir/genscripts'.
       Prerequisite `stampdir/stampdir' is older than target `stampdir/genscripts'.
      No need to remake target `stampdir/genscripts'.
     Finished prerequisites of target file `stampdir/prepare'.
     Prerequisite `stampdir/log' is newer than target `stampdir/prepare'.
     Prerequisite `stampdir/genscripts' is older than target `stampdir/prepare'.
    Must remake target `stampdir/prepare'.
[...]

You can reproduce this problem with the xserver-xorg-video-fbdev
package.

Sven