messages: avoid SHA-1 in end-user facing messages

There are still a handful mentions of SHA-1 when we meant the
(hexadecimal) object names in end-user facing messages.  Rewrite
them.

I was hoping that this can mostly be s/SHA-1/object name/, but
a few messages needed rephrasing to keep the result readable.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/pack-objects.c

@@ -3325,7 +3325,7 @@ static void get_object_list(int ac, const char **av)
 			if (starts_with(line, "--shallow ")) {
 				struct object_id oid;
 				if (get_oid_hex(line + 10, &oid))
-					die("not an SHA-1 '%s'", line + 10);
+					die("not an object name '%s'", line + 10);
 				register_shallow(the_repository, &oid);
 				use_bitmap_index = 0;
 				continue;