Fix converted media being saved with original extension and mime type (#11130)

lib/paperclip/type_corrector.rb

@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+require 'mime/types/columnar'
+
+module Paperclip
+  class TypeCorrector < Paperclip::Processor
+    def make
+      target_extension = options[:format]
+      extension        = File.extname(attachment.instance.file_file_name)
+
+      return @file unless options[:style] == :original && target_extension && extension != target_extension
+
+      attachment.instance.file_content_type = options[:content_type] || attachment.instance.file_content_type
+      attachment.instance.file_file_name    = File.basename(attachment.instance.file_file_name, '.*') + '.' + target_extension
+
+      @file
+    end
+  end
+end