EE fixes

app/models/resource_label_event.rb

 class ResourceLabelEvent < ActiveRecord::Base
+  prepend EE::ResourceLabelEvent
+
   ISSUABLE_COLUMNS = %i(issue_id merge_request_id).freeze
 
   belongs_to :user

db/migrate/20180726172057_create_resource_label_events.rb

@@ -8,6 +8,7 @@ class CreateResourceLabelEvents < ActiveRecord::Migration
       t.integer :action, null: false
       t.references :issue, null: true, index: true, foreign_key: { on_delete: :cascade }
       t.references :merge_request, null: true, index: true, foreign_key: { on_delete: :cascade }
+      t.references :epic, null: true, index: true, foreign_key: { on_delete: :cascade }
       t.references :label, index: true, foreign_key: { on_delete: :nullify }
       t.references :user, index: true, foreign_key: { on_delete: :nullify }
       t.datetime_with_timezone :created_at, null: false

db/schema.rb

@@ -2361,11 +2361,13 @@ ActiveRecord::Schema.define(version: 20180726172057) do
     t.integer "action", null: false
     t.integer "issue_id"
     t.integer "merge_request_id"
+    t.integer "epic_id"
     t.integer "label_id"
     t.integer "user_id"
     t.datetime_with_timezone "created_at", null: false
   end
 
+  add_index "resource_label_events", ["epic_id"], name: "index_resource_label_events_on_epic_id", using: :btree
   add_index "resource_label_events", ["issue_id"], name: "index_resource_label_events_on_issue_id", using: :btree
   add_index "resource_label_events", ["label_id"], name: "index_resource_label_events_on_label_id", using: :btree
   add_index "resource_label_events", ["merge_request_id"], name: "index_resource_label_events_on_merge_request_id", using: :btree
@@ -3031,6 +3033,7 @@ ActiveRecord::Schema.define(version: 20180726172057) do
   add_foreign_key "push_rules", "projects", name: "fk_83b29894de", on_delete: :cascade
   add_foreign_key "releases", "projects", name: "fk_47fe2a0596", on_delete: :cascade
   add_foreign_key "remote_mirrors", "projects", name: "fk_43a9aa4ca8", on_delete: :cascade
+  add_foreign_key "resource_label_events", "epics", on_delete: :cascade
   add_foreign_key "resource_label_events", "issues", on_delete: :cascade
   add_foreign_key "resource_label_events", "labels", on_delete: :nullify
   add_foreign_key "resource_label_events", "merge_requests", on_delete: :cascade

ee/app/models/ee/epic.rb

@@ -9,6 +9,7 @@ module EE
       include Noteable
       include Referable
       include Awardable
+      include LabelEventable
 
       belongs_to :assignee, class_name: "User"
       belongs_to :group

ee/app/models/ee/resource_label_event.rb

+module EE
+  module ResourceLabelEvent
+    extend ActiveSupport::Concern
+    extend ::Gitlab::Utils::Override
+
+    EE_ISSUABLE_COLUMNS = %i(epic_id).freeze
+
+    override :issuable
+    def issuable
+      epic || super
+    end
+
+    override :issuable_columns
+    def issuable_columns
+      EE_ISSUABLE_COLUMNS + super
+    end
+  end
+end