The testcase t1400 exercises the git-update-ref(1) utility. To do so, many tests directly read and write references via the filesystem, assuming that we always use loose and/or packed references. While this is true now, it'll change with the introduction of the reftable backend. Convert those tests to use git-update-ref(1) and git-show-ref(1) where possible. Furthermore, two tests are converted to not delete HEAD anymore, as this results in a broken repository. They've instead been updated to create a non-mandatory symbolic reference and delete that one instead. Some tests remain which exercise behaviour with broken references, which cannot currently be converted to use regular git tooling. Signed-off-by: Patrick Steinhardt <ps@pks.im> Reviewed-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>