On the button that says ‘Revert to revision’ does revision mean draft/version?
(When you do revert, the message in History says ‘reverted to version #x’, so I assume it does)
If it does, here’s a related bug (I think it makes more sense to address both in a single patch):
Create a new topic → (Title1, Text1)
Edit title only → (Title2, Text1)
Edit text only → (Title2, Text2)
Revert to the first draft
Expected output: (Title1, Text1)
Actual output: (Title1, Text2), which incidentally isn’t any of the drafts
You can change text first and title second with similar effect or use category instead of either title or text.