https://musicbrainz.org/release/a11b3cc1-27af-4ae5-b9b3-6e0917ef4ceb
https://musicbrainz.org/edit/22818297

Attempting to add a release without tracknumbers is impossible. As a kludgy workaround, it is currently possible to make an "Edit medium" which removes the tracknumbers which are automatically added. (note that a hole in the edit system currently allows all tracknumber edits to be autoedits.)

Another example better demonstrating the magical data:
https://musicbrainz.org/release/a6a265bf-9f81-4055-8224-f7ac0aa6b937/edits
Edit #25991659 is undoing a data change that doesn't have an edit.

I can't imagine how awful it must be that the "Add Medium" and "Edit Medium" code must be maintained separately!