Pull request does not close automatically after having merged locally via hg (BB-11321)

Happens in Mercurial (hg) repos.

Several months ago pull requests were automatically marked as merged if the corresponding merge happened in the repo.

Now the autoclose does not happen, and after a manual merge, the pull request remains open but displays 0 files changed. After that, I have to either hit Merge and have an extra pair of commits, or hit Decline which is not what's intended.

Sorry if I created a duplicate. I could not find any related issues.