The IssueNotifier will try to assign a user to an issue if there is no assignee when an issue is resolved. If this fails, the whole workitem fails and is retried later. In the case where the user in question is marked as inactive in JBS, this will continue failing indefinitely, or until the user is marked active again, effectively blocking notifications for all commits after the affected one. The return code from Jira is 400 and the error message looks like this:

{"errorMessages":[],"errors":{"assignee":"User 'foo' cannot be assigned issues."}}

I think we should try to detect this situation and just skip assigning the user in that case (and add a clear log message to indicate this happened).

The workaround if this situation is encountered is to temporarily assign a different user as assignee to the offending issue. The IssueNotifier will then skip trying to assign and move ahead with the next commit.