completion: simplify tests using test_completion_long()

diff --git a/t/t4150-am.sh b/t/t4150-am.sh
index ccc0280f52232e845f9d7c7bd5c3326b412d4a96..cdafd7e7c1e6c73a97c36a60f77810badff603f2 100755 (executable)
--- a/t/t4150-am.sh
+++ b/t/t4150-am.sh
@@ -525,9 +525,9 @@ test_expect_success 'am empty-file does not infloop' '
        git reset --hard &&
        touch empty-file &&
        test_tick &&
-       { git am empty-file > actual 2>&1 && false || :; } &&
+       test_must_fail git am empty-file 2>actual &&
        echo Patch format detection failed. >expected &&
-       test_cmp expected actual
+       test_i18ncmp expected actual
 '
 
 test_done