xread/xwrite: clip MAX_IO_SIZE to SSIZE_MAX

diff --git a/t/t3900-i18n-commit.sh b/t/t3900-i18n-commit.sh
index 38b00c37b0606a5442f2dce02647a019f0c80c9e..4bf1dbe9c9f3ffeb1151be07bf75dcd872167916 100755 (executable)
--- a/t/t3900-i18n-commit.sh
+++ b/t/t3900-i18n-commit.sh
@@ -34,9 +34,9 @@ test_expect_success 'no encoding header for base case' '
        test z = "z$E"
 '
 
-test_expect_failure 'UTF-16 refused because of NULs' '
+test_expect_success 'UTF-16 refused because of NULs' '
        echo UTF-16 >F &&
-       git commit -a -F "$TEST_DIRECTORY"/t3900/UTF-16.txt
+       test_must_fail git commit -a -F "$TEST_DIRECTORY"/t3900/UTF-16.txt
 '
 
 test_expect_success 'UTF-8 invalid characters refused' '