t4045: abstract away SHA-1-specific constants

diff --git a/t/t2011-checkout-invalid-head.sh b/t/t2011-checkout-invalid-head.sh
index c5501b008c8f56ac0712d9f475ebc460a0d4eea4..0e8d56aa7631cb30eebd468abe8d93f720d92913 100755 (executable)
--- a/t/t2011-checkout-invalid-head.sh
+++ b/t/t2011-checkout-invalid-head.sh
@@ -15,7 +15,7 @@ test_expect_success 'checkout should not start branch from a tree' '
 '
 
 test_expect_success 'checkout master from invalid HEAD' '
-       echo $_z40 >.git/HEAD &&
+       echo $ZERO_OID >.git/HEAD &&
        git checkout master --
 '