If an existing packaging entry is present for the other end of the link, we stop the user: he shouldn't be allowed to overwrite an existing primary packaging link. This would actually be valid when a package was renamed within a release, but that might be best ignored here.
If an existing packaging entry is present for the other end of the link, we stop the user: he shouldn't be allowed to overwrite an existing primary packaging link. This would actually be valid when a package was renamed within a release, but that might be best ignored here.