Was: [Bug] Tag history entries might be merging?

Bug overview description.
I'm quite certain that the only tag I added to post #966846 was unusual_penis. However, the tag history on that post also shows me adding sex and replacing 3_eyes with third_eye. I question my sanity.

What part(s) of the site page(s) are affected?
The tag history for that post: https://e621.net/post_tag_history/index?post_id=966846
My tag edits: https://e621.net/post_tag_history?user_id=205175

What is the expected behavior?
Tag edits attributed to me should only show changes that I actually made.

What actual behavior is given instead?
The tag edit additionally shows changes that actually happened, and that make sense for the post, but that were not made by me.

Time of incident (if applicable).
I made the edit sometime yesterday (December 2nd, 2017). I noticed the weirdness just now.

Can you reproduce the bug every time?
No. I don't see this on any of my other tag edits.

What steps did you take to replicate this bug?
I've just added a single tag to post #1392948. Maybe if the next edit is someone else removing one tag and adding two tags, it will happen again.

Errors or other messages returned (if any).
None.

It's an aliasing issue. 3_eyes A-> third_eye was aliased after MeatyLoaf's edit so it doesn't show up there. Your edit made the system realise that change wasn't accounted for. Ditto for handjob I-> sex. If the alias/implication was made after the previous edit (in this case, MeatyLoaf's), it shows up in the next one (in this case, yours).

BlueDingo said:
It's an aliasing issue. 3_eyes A-> third_eye was aliased after MeatyLoaf's edit so it doesn't show up there. Your edit made the system realise that change wasn't accounted for. Ditto for handjob I-> sex. If the alias/implication was made after the previous edit (in this case, MeatyLoaf's), it shows up in the next one (in this case, yours).

Well spotted.

This is probably still a bug, but I at least feel better knowing that there isn't some lurking race condition causing people's edits to be sporadically lost.

Maxpizzle said:
Well spotted.

This happened to me a lot when I was editing really old posts that no one had even looked at for years, let alone tagged.

Maxpizzle said:
This is probably still a bug, but I at least feel better knowing that there isn't some lurking race condition causing people's edits to be sporadically lost.

A completely harmless and self-correcting one. I don't think there is anything you can do about it since alias/implication approvals don't create entries in the tag history and would probably result in a lot of auto-entries showing up if they did.

Maybe when a user makes such a tag edit, the system could autogenerate a separate history entry attributed to the system instead of lumping the automatic tag changes in with the user?