t5317: stop losing return codes of git ls-files
fb2d0db502 (test-lib-functions: add parsing helpers for ls-files and
ls-tree, 2022-04-04) not only started to use helper functions, it also
started to pipe the output of git ls-files into them directly, without
using a temporary file. No explanation was given. This causes the
return code of that git command to be ignored.
Revert that part of the change, use temporary files and check the return
code of git ls-files again.
Suggested-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>