Merge tag 'v1.6.0rc4' into sync/upstream-1.6.0rc4

Conflicts:
      app/javascript/mastodon/features/getting_started/index.js
      app/javascript/packs/public.js
      app/javascript/styles/components.scss

app/lib/activitypub/tag_manager.rb

@@ -96,12 +96,14 @@ class ActivityPub::TagManager
       when 'Account'
         klass.find_local(uri_to_local_id(uri, :username))
       else
-        klass.find_by(id: uri_to_local_id(uri))
+        StatusFinder.new(uri).status
       end
     elsif ::TagManager.instance.local_id?(uri)
       klass.find_by(id: ::TagManager.instance.unique_tag_to_local_id(uri, klass.to_s))
     else
       klass.find_by(uri: uri.split('#').first)
     end
+  rescue ActiveRecord::RecordNotFound
+    nil
   end
 end

app/lib/language_detector.rb

@@ -20,7 +20,16 @@ class LanguageDetector
   private
 
   def detected_language_code
-    result.language.to_sym if detected_language_reliable?
+    iso6391(result.language).to_sym if detected_language_reliable?
+  end
+
+  def iso6391(bcp47)
+    iso639 = bcp47.split('-').first
+
+    # CLD3 returns grandfathered language code for Hebrew
+    return 'he' if iso639 == 'iw'
+
+    ISO_639.find(iso639).alpha2
   end
 
   def result