FIX: Show the envelope icon when the flagged post is a PM. Flagged PM must be exclusively reviewed by admins (#9232)

app/assets/javascripts/discourse/templates/components/reviewable-topic-link.hbs

@@ -1,6 +1,6 @@
 <div class='post-topic'>
   {{#if reviewable.topic}}
-    {{topic-status topic=reviewable.topic}}
+    {{topic-status topic=reviewable.topic showPrivateMessageIcon=true}}
     <a href={{reviewable.target_url}} class='title-text'>{{reviewable.topic.title}}</a>
     {{category-badge reviewable.category}}
     {{reviewable-tags tags=reviewable.topic_tags tagName=''}}

app/models/reviewable.rb

@@ -133,7 +133,7 @@ class Reviewable < ActiveRecord::Base
       target: target,
       topic: topic,
       created_by: created_by,
-      reviewable_by_moderator: reviewable_by_moderator,
+      reviewable_by_moderator: reviewable_by_moderator && !(topic&.private_message?),
       payload: payload,
       potential_spam: potential_spam
     )

spec/models/reviewable_spec.rb

@@ -78,6 +78,17 @@ RSpec.describe Reviewable, type: :model do
       expect(r1.pending?).to eq(true)
       expect(r0.pending?).to eq(false)
     end
+
+    it 'sets the reviewable_by_moderator attribute to false when the topic is a PM' do
+      pm_topic = Fabricate(:private_message_topic)
+      post = Fabricate(:post, topic: pm_topic)
+      reviewable = ReviewableFlaggedPost.needs_review!(
+        target: post, topic: pm_topic,
+        created_by: Discourse.system_user, reviewable_by_moderator: true
+      )
+
+      expect(reviewable.reviewable_by_moderator).to eq(false)
+    end
   end
 
   context ".list_for" do