pack-objects: document about thread synchronization

diff --git a/t/t1601-index-bogus.sh b/t/t1601-index-bogus.sh
index 73cc9323cdc2a40105bd6218983381b8a72b381a..4171f1e14103135ef3e47a3b3df19d5a285b4a8a 100755 (executable)
--- a/t/t1601-index-bogus.sh
+++ b/t/t1601-index-bogus.sh
@@ -4,7 +4,7 @@ test_description='test handling of bogus index entries'
 . ./test-lib.sh
 
 test_expect_success 'create tree with null sha1' '
-       tree=$(printf "160000 commit $_z40\\tbroken\\n" | git mktree)
+       tree=$(printf "160000 commit $ZERO_OID\\tbroken\\n" | git mktree)
 '
 
 test_expect_success 'read-tree refuses to read null sha1' '