Don't create event in Merge Request Create Service

app/services/merge_requests/create_service.rb

@@ -25,7 +25,6 @@ module MergeRequests
     end
 
     def after_create(issuable)
-      event_service.open_mr(issuable, current_user)
       todo_service.new_merge_request(issuable, current_user)
       issuable.cache_merge_request_closes_issues!(current_user)
       update_merge_requests_head_pipeline(issuable)

db/post_migrate/20170815060945_remove_duplicate_mr_events.rb

+# See http://doc.gitlab.com/ce/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class RemoveDuplicateMrEvents < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+  DOWNTIME = false
+
+  class Event < ActiveRecord::Base
+    self.table_name = 'events'
+  end
+
+  def up
+    base_condition = "action = 1 AND target_type = 'MergeRequest' AND created_at > '2017-08-13'"
+    Event.select('target_id, count(*)')
+      .where(base_condition)
+      .group('target_id').having('count(*) > 1').each do |event|
+      duplicates = Event.where("#{base_condition} AND target_id = #{event.target_id}").pluck(:id)
+      duplicates.shift
+
+      Event.where(id: duplicates).delete_all
+    end
+  end
+
+  def down
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20170809161910) do
+ActiveRecord::Schema.define(version: 20170815060945) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"

spec/migrations/remove_duplicate_mr_events_spec.rb

+require 'spec_helper'
+require Rails.root.join('db', 'post_migrate', '20170815060945_remove_duplicate_mr_events.rb')
+
+describe RemoveDuplicateMrEvents, truncate: true do
+  let(:migration) { described_class.new }
+
+  describe '#up' do
+    let(:user) { create(:user) }
+    let(:merge_requests) { create_list(:merge_request, 2) }
+    let(:issue) { create(:issue) }
+    let!(:events) do
+      [
+        create(:event, :created, author: user, target: merge_requests.first),
+        create(:event, :created, author: user, target: merge_requests.first),
+        create(:event, :updated, author: user, target: merge_requests.first),
+        create(:event, :created, author: user, target: merge_requests.second),
+        create(:event, :created, author: user, target: issue),
+        create(:event, :created, author: user, target: issue)
+      ]
+    end
+
+    it 'removes duplicated merge request create records' do
+      expect { migration.up }.to change { Event.count }.from(6).to(5)
+    end
+  end
+end

spec/services/merge_requests/create_service_spec.rb

@@ -48,6 +48,16 @@ describe MergeRequests::CreateService do
         expect(Todo.where(attributes).count).to be_zero
       end
 
+      it 'creates exactly 1 create MR event' do
+        attributes = {
+          action: Event::CREATED,
+          target_id: @merge_request.id,
+          target_type: @merge_request.class.name
+        }
+
+        expect(Event.where(attributes).count).to eq(1)
+      end
+
       context 'when merge request is assigned to someone' do
         let(:opts) do
           {