more tr portability test script fixes

diff --git a/t/t4020-diff-external.sh b/t/t4020-diff-external.sh
index ed3bd5b3fe7c8b5ca52067e3015e0d770ee79bf2..bf8f778a471b7fdb21b6e6df473222593439ba34 100755 (executable)
--- a/t/t4020-diff-external.sh
+++ b/t/t4020-diff-external.sh
@@ -99,7 +99,7 @@ test_expect_success 'no diff with -diff' '
        git diff | grep Binary
 '
 
-echo NULZbetweenZwords | tr Z '\0' > file
+echo NULZbetweenZwords | perl -pe 'y/Z/\000/' > file
 
 test_expect_success 'force diff with "diff"' '
        echo >.gitattributes "file diff" &&