builtin/am: introduce write_state_*() helper functions

diff --git a/builtin/update-ref.c b/builtin/update-ref.c
index 160c7ac1d3c63d6acfea5794958e27eac9ab159e..6763cf1837db99442a7140fe5bb87a0b3a1248fd 100644 (file)
--- a/builtin/update-ref.c
+++ b/builtin/update-ref.c
@@ -422,7 +422,13 @@ int cmd_update_ref(int argc, const char **argv, const char *prefix)
        if (no_deref)
                flags = REF_NODEREF;
        if (delete)
-               return delete_ref(refname, oldval ? oldsha1 : NULL, flags);
+               /*
+                * For purposes of backwards compatibility, we treat
+                * NULL_SHA1 as "don't care" here:
+                */
+               return delete_ref(refname,
+                                 (oldval && !is_null_sha1(oldsha1)) ? oldsha1 : NULL,
+                                 flags);
        else
                return update_ref(msg, refname, sha1, oldval ? oldsha1 : NULL,
                                  flags, UPDATE_REFS_DIE_ON_ERR);