tests: don't let a fail=1 env. setting induce unwarranted test failure

* cfg.mk (sc_fail_is_initialized): New rule.
Fix the offenders:
* tests/cp/acl: Set fail=0
* tests/cp/backup-is-src: Likewise.
* tests/cp/file-perm-race: Likewise.
* tests/cp/reflink-auto: Likewise.
* tests/cp/same-file: Likewise.
* tests/ln/backup-1: Likewise.
* tests/misc/su-fail: Likewise.
* tests/misc/truncate-owned-by-other: Likewise.
* tests/mkdir/p-3: Likewise.
* tests/mkdir/selinux: Likewise.
* tests/mkdir/special-1: Likewise.
* tests/mv/acl: Likewise.
* tests/mv/backup-is-src: Likewise.
* tests/mv/diag: Likewise.
* tests/mv/force: Likewise.
* tests/mv/hard-link-1: Likewise.
* tests/mv/into-self-3: Likewise.
* tests/mv/sticky-to-xpart: Likewise.
* tests/touch/now-owned-by-other: Likewise.

1 files changed, 11 insertions, 0 deletions

diff --git a/cfg.mk b/cfg.mk
index 1e5108b2d..c3a7afe5e 100644
--- a/cfg.mk
+++ b/cfg.mk
@@ -230,4 +230,15 @@ sc_prohibit_emacs__indent_tabs_mode__setting:
 	msg='use of emacs indent-tabs-mode: setting'			\
 	  $(_prohibit_regexp)
 
+# Ensure that each file that contains fail=1 also contains fail=0.
+# Otherwise, setting file=1 in the environment would make tests fail unexpectedly.
+sc_fail_is_initialized:
+	@files=$$(grep -l -E '\<fail=1$$' $$($(VC_LIST_EXCEPT)));	\
+	if test "$$?" = 0; then						\
+	  grep -LE '\<fail=0$$' $$files | grep . &&			\
+	    { echo '$(ME): the above files do not set fail=0'		\
+		1>&2; exit 1; } || :;					\
+	else :;								\
+	fi
+
 include $(srcdir)/dist-check.mk