Bug overview description.
I noticed it was possible to undo tag edits on deleted posts. Since you are not allowed to revert tag edits on deleted posts, I figured this was maybe unintentional behavior. Not really that important, just figured I'd toss that out here just in case.

What part(s) of the site page(s) are affected?
Tags on deleted posts.

What is the expected behavior?
I'm assuming that since you aren't allowed to revert tags on deleted posts, you shouldn't be able to undo tag edits either.

What actual behavior is given instead?
You are allowed to undo tag edits on deleted posts.

Time of incident (if applicable).
N/A.

Can you reproduce the bug every time?
Yes.

What steps did you take to replicate this bug?
Go to tag history of a deleted post, hit undo on one of the changes.

Errors or other messages returned (if any).
N/A.

Given that it's possible for people to edit deleted posts already, we're going to allow this. It may not be fully intentional, but it also isn't a big issue either. I don't know why revert is explicitly disabled on deleted posts, but generally that is used for moderation purposes anyways, so also not a big deal.