Merge requests should list the "addressed issues"
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### Description
Commits can refer to an issue via a commit message like this
```
Summary
Description
#1 #2 #5
```
If I afterwards create a merge Request for a branch containing such commits, I would like to see the addressed issues listed directly in the merge request's description.
I am pretty sure that I saw such a list in an earlier version of GitLab CE but it is apparently not present in the current one.
### Feature checklist
Make sure these are completed before closing the issue,
with a link to the relevant commit.
- [ ] [Feature assurance](https://about.gitlab.com/handbook/product/#feature-assurance)
- [ ] Documentation
- [ ] Added to [features.yml](https://gitlab.com/gitlab-com/www-gitlab-com/blob/master/data/features.yml)
issue