Wrong "iid of max iid" in issuable sidebar for some merged MRs

The "iid of max iid" in issuable sidebar doesn't scope merged MR (my bad):

In issuables_helper.rb:

def issuable_state_scope(issuable)
  issuable.open? ? :opened : :closed
end

Example in !3011 (merged):

mentioned in merge request !3046 (merged)

mentioned in commit e632bd26

Milestone changed to 8.6

Status changed to closed by commit e632bd26

mentioned in commit 6f50cef8