merge with /dev/null as base, instead of punting O==empty case

diff --git a/update-ref.c b/update-ref.c
index 65dc3d6385756a11aac257a3ed6a9dfcb68cce53..d79dc52fd7d1eb1117e37c6b400c5f99bc8e4fcd 100644 (file)
--- a/update-ref.c
+++ b/update-ref.c
@@ -42,7 +42,7 @@ int main(int argc, char **argv)
 
        if (oldval) {
                if (memcmp(currsha1, oldsha1, 20))
-                       die("Ref %s changed to %s", refname, sha1_to_hex(currsha1));
+                       die("Ref %s is at %s but expected %s", refname, sha1_to_hex(currsha1), sha1_to_hex(oldsha1));
                /* Nothing to do? */
                if (!memcmp(oldsha1, sha1, 20))
                        exit(0);