Ok. This is a little bit subtle. I naively tried to simplify the fields by using this:
Replaces: dialog (<< 1.3-20240307) Breaks: dialog (<< 1.3-20240307) But this actually means upstream version 1.3, debian revision 20240307, not upstream 1.3-20240307. I guess I should use 1.3-20240307-0 at minimum. Thanks.