Merge branch 'master' into glitch-soc/merge-upstream

Conflicts:
- app/controllers/application_controller.rb
  Minor conflict due to glitch-soc's theming system

app/models/media_attachment.rb

@@ -167,6 +167,18 @@ class MediaAttachment < ApplicationRecord
     audio? || video?
   end
 
+  def variant?(other_file_name)
+    return true if file_file_name == other_file_name
+
+    formats = file.styles.values.map(&:format).compact
+
+    return false if formats.empty?
+
+    extension = File.extname(other_file_name)
+
+    formats.include?(extension.delete('.')) && File.basename(other_file_name, extension) == File.basename(file_file_name, File.extname(file_file_name))
+  end
+
   def to_param
     shortcode
   end