New draft created at each autosave

Description

Steps to reproduce:

1. Create a project.
2. Edit an existing page to create a new draft and to associate it with the project.
3. Log out of CMS while having the project active.
4. Log in as a different user.
5. Delete the project and log out.
6. Log in again as the first user who created the project.
7. Edit the draft that was previously associated with (the now deleted) project.

Expected result: No new draft is created, and It should be possible to edit the draft as normal. The published version is still set as primary draft.

Actual result: In the versions gadget, every edit of the page creates a new draft. The published version is still the primary draft.