If a merge request in Gitlab is merged manually by someone using the Gitlab "merge" button instead of through Skara, the mlbridge bot will get stuck in a retry loop hitting NPE.

The mlbridge wants to send a notice about the MR having been closed, but Gitlab doesn't think the MR was closed, it regards it as integrated. Mlbridge tries to lookup the field "closed_by", which is null in this case, and causes the NPE.

The retry will continue until the MR gets old enough to no longer be included in the query (currently 14 days since last being touched).