Somehow differentiate between "done" issues and issues that were closed for other reasons

Description

Sometimes we close issues when they're not done. e.g. moving an issue from gitlab-ce to gitlab-ee, or closing an issue because it's content has been subsumed by another issue. But these closed-but-not-done issues show up in issue boards as "done", which is confusing. I don't know what the solution is, but we should do something.

Proposal

Links / references