i18n: do not overuse C_LOCALE_OUTPUT (grep)

Instead of skipping the whole test, introduce test_i18ngrep wrapper that
pretends a successful result under GETTEXT_POISON build.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t0001-init.sh

@@ -180,7 +180,7 @@ test_expect_success 'GIT_DIR & GIT_WORK_TREE (2)' '
 	fi
 '
 
-test_expect_success C_LOCALE_OUTPUT 'reinit' '
+test_expect_success 'reinit' '
 
 	(
 		sane_unset GIT_CONFIG GIT_WORK_TREE GIT_CONFIG &&
@@ -190,11 +190,11 @@ test_expect_success C_LOCALE_OUTPUT 'reinit' '
 		git init >out1 2>err1 &&
 		git init >out2 2>err2
 	) &&
-	grep "Initialized empty" again/out1 &&
-	grep "Reinitialized existing" again/out2 &&
+	test_i18ngrep "Initialized empty" again/out1 &&
+	test_i18ngrep "Reinitialized existing" again/out2 &&
 	>again/empty &&
-	test_cmp again/empty again/err1 &&
-	test_cmp again/empty again/err2
+	test_i18ncmp again/empty again/err1 &&
+	test_i18ncmp again/empty again/err2
 '
 
 test_expect_success 'init with --template' '

t/test-lib.sh

@@ -1085,6 +1085,24 @@ test_i18ncmp () {
 	test -n "$GETTEXT_POISON" || test_cmp "$@"
 }
 
+# Use this instead of "grep expected-string actual" to see if the
+# output from a git command that can be translated either contains an
+# expected string, or does not contain an unwanted one.  When running
+# under GETTEXT_POISON this pretends that the command produced expected
+# results.
+test_i18ngrep () {
+	if test -n "$GETTEXT_POISON"
+	then
+	    : # pretend success
+	elif test "x!" = "x$1"
+	then
+		shift
+		! grep "$@"
+	else
+		grep "$@"
+	fi
+}
+
 # test whether the filesystem supports symbolic links
 ln -s x y 2>/dev/null && test -h y 2>/dev/null && test_set_prereq SYMLINKS
 rm -f y