Do not set closed_at to nil when issue is reopened

app/models/issue.rb

@@ -59,10 +59,6 @@ class Issue < ActiveRecord::Base
     before_transition any => :closed do |issue|
       issue.closed_at = Time.zone.now
     end
-
-    before_transition closed: any do |issue|
-      issue.closed_at = nil
-    end
   end
 
   def hook_attrs

changelogs/unreleased/issue_91_ee_backport.yml

@@ -0,0 +1,4 @@
+---
+title: Do not set closed_at to nil when issue is reopened
+merge_request:
+author:

spec/models/issue_spec.rb

@@ -51,14 +51,6 @@ describe Issue, models: true do
 
       expect(issue.closed_at).to eq(now)
     end
-
-    it 'sets closed_at to nil when issue is reopened' do
-      issue = create(:issue, state: 'closed')
-
-      issue.reopen
-
-      expect(issue.closed_at).to be_nil
-    end
   end
 
   describe '#to_reference' do