Close issues mentioned in MR description when MR is merged using fast-forward merge or when merge commit message is edited.
Fixes gitlab-org/gitlab-ee#48.
@rspeicher This was an 8.0 regression, so please get it into 8.1!
Fixes gitlab-org/gitlab-ee#48.
@rspeicher This was an 8.0 regression, so please get it into 8.1!