### Summary Merging a merge request that has `Closes #123` in both - merge request description and one of the commit messages, closes issue twice. ### What is the current *bug* behavior?  Only the first close event is effective. ### What is the expected *correct* behavior? Issue should be closed by merger first (to be consistent with what happens when there is no `Closes #123` in commit messages), the second event should be ignored. Similar to https://gitlab.com/gitlab-org/gitlab-ce/issues/21493. I created a separate issue to keep track on decision which user will close the issue, because this is not a case in gitlab-ce#21493. /cc @smcgivern