vpath and make dist newbie problem

[Dan Kegel]

I don't understand automake's "make dist" support, and could use a clue.
I've boiled my problem down to the following tiny test case, in which
"./configure; make" works, but "make dist" fails.  It seems that
make dist is unable to follow vpath.  Is this a known problem?

To reproduce the problem, do
  wget http://kegel.com/pathprob.tgz
  tar -xzvf pathprob.tgz
  cd pathprob
  touch NEWS README AUTHORS ChangeLog
  aclocal
  autoconf
  automake --add-missing
  ./configure
  make dist

This outputs
{ test ! -d "foo-0.1" || { find "foo-0.1" -type d ! -perm -200 -exec
chmod u+w {} ';' && rm -fr "foo-0.1"; }; }
test -d "foo-0.1" || mkdir "foo-0.1"
 (cd foobar && make  top_distdir=../foo-0.1 distdir=../foo-0.1/foobar \
     am__remove_distdir=: am__skip_length_check=: am__skip_mode_fix=: distdir)
make[1]: Entering directory `/home/dank/pathprob/foobar'
cp: cannot stat `./george.c': No such file or directory
make[1]: *** [distdir] Error 1
make[1]: Leaving directory `/home/dank/pathprob/foobar'
make: *** [distdir] Error 1

The test case consists of the four files
pathprob/Makefile.am pathprob/foobar/Makefile.am
pathprob/foobar/blah/george.c pathprob/configure.ac
with contents

::::::::::::::
pathprob/Makefile.am
::::::::::::::
SUBDIRS = foobar
::::::::::::::
pathprob/foobar/Makefile.am
::::::::::::::
AUTOMAKE_OPTIONS = \
  foreign \
  1.9 \
  --warnings=no-portability

lib_LIBRARIES = libfoobar.a

vpath %.c @abs_srcdir@/blah

libfoobar_a_SOURCES = george.c
::::::::::::::
pathprob/foobar/blah/george.c
::::::::::::::
int x = 1;
::::::::::::::
pathprob/configure.ac
::::::::::::::
AC_PREREQ(2.61)
AC_INIT([foo],
        [0.1],
        address@hidden,
        [foo])
AC_PROG_CC
AC_PROG_RANLIB
AM_INIT_AUTOMAKE

AC_CONFIG_FILES([
        Makefile
        foobar/Makefile
])
AC_OUTPUT

This is with automake 1.11.1 and autoconf 2.65.