i18n: use test_i18n{cmp,grep} in t7600, t7607, t7611 and t7811

Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/t/t7611-merge-abort.sh b/t/t7611-merge-abort.sh
index cdb3f44..7b4798e 100755
--- a/t/t7611-merge-abort.sh
+++ b/t/t7611-merge-abort.sh
@@ -46,11 +46,8 @@
 pre_merge_head="$(git rev-parse HEAD)"
 
 test_expect_success 'fails without MERGE_HEAD (unstarted merge)' '
-	test_must_fail git merge --abort 2>output
-'
-
-test_expect_success C_LOCALE_OUTPUT 'fails without MERGE_HEAD (unstarted merge): fatal output' '
-	grep -q MERGE_HEAD output
+	test_must_fail git merge --abort 2>output &&
+	test_i18ngrep MERGE_HEAD output
 '
 
 test_expect_success 'fails without MERGE_HEAD (unstarted merge): .git/MERGE_HEAD sanity' '
@@ -63,11 +60,8 @@
 	test ! -f .git/MERGE_HEAD &&
 	# Merge successfully completed
 	post_merge_head="$(git rev-parse HEAD)" &&
-	test_must_fail git merge --abort 2>output
-'
-
-test_expect_success C_LOCALE_OUTPUT 'fails without MERGE_HEAD (completed merge): output' '
-	grep -q MERGE_HEAD output
+	test_must_fail git merge --abort 2>output &&
+	test_i18ngrep MERGE_HEAD output
 '
 
 test_expect_success 'fails without MERGE_HEAD (completed merge): .git/MERGE_HEAD sanity' '