doc/fast-import: clarify how content states are built

diff --git a/t/t1400-update-ref.sh b/t/t1400-update-ref.sh
index ff747f8229bb46df070ea9aad2702f4d1c703420..4fd83a667ac8b08bef090d303bc4434969874780 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=0000000000000000000000000000000000000000
+Z=$_z40
 
 test_expect_success setup '