t4208: abstract away SHA-1-specific constants

diff --git a/t/t1400-update-ref.sh b/t/t1400-update-ref.sh
index 664a3a4e4e9b81d3e017c22414b0bbe2ef25b83a..f6dc05654ea5a2f06b41d8c300f8916b2e773972 100755 (executable)
--- a/t/t1400-update-ref.sh
+++ b/t/t1400-update-ref.sh
@@ -6,7 +6,7 @@
 test_description='Test git update-ref and basic ref logging'
 . ./test-lib.sh
 
-Z=$_z40
+Z=$ZERO_OID
 
 m=refs/heads/master
 n_dir=refs/heads/gu