Merged pull not marked as merged when conflict checking still in progress

[fnetX]

Description

Merging a pull request on the web UI doesn't mark it as merged when the conflict checking is still in progres.

1. Merge PR A.
2. Navigate to PR B and merge it, while the conflict checking after the first merge is still in progress.
3. See that the PR is merged (merge commit exists in the target branch), but the PR is not marked as merged.
4. The already-merged PR B still shows the "conflict checking still in progress" information

I encountered this on Codeberg, here: https://codeberg.org/Codeberg/Documentation/pulls/211 (the PR was marked as manually merged, but the actual merge happend using the web UI). I couldn't reproduce on try.gitea.io, but I suppose it's a timing issue with the merge conflict checker, I didn't manage to get into a state where I could see the "Conflict checking still in progress window" (but I saw this on Codeberg after B was merged).

CC @Gusted

Gitea Version

1.16.5

Can you reproduce the bug on the Gitea demo site?

No

Log Gist

No response

Screenshots

Git Version

No response

Operating System

Debian GNU/Linux

How are you running Gitea?

Codeberg deployment (manually compiled custom fork), run without container on a Debian Linux machine.

Database

MySQL