Currently, rollbacks are never rolled into the previous revision.
I propose a simple change making the rollback-link more useful:
If the rollback is to the pre-edit revision, and an ordinary edit would be rolled into the previous revision, just pretend it was one.
(The resulting empty revision has the summary
[Edit removed during grace period].)
That avoids recording any more evidence than necessary of the brain-fart which led to the edit, reducing embarrassment and avoiding puzzlement to readers by de-cluttering the revision-history.
If the edit-notification was not yet signalled to the user, squash it. After all, there's nothing to see.