--- redmine_old/app/models/attachment.rb	2017-11-30 16:39:53.579217799 +0500
+++ redmine_new/app/models/attachment.rb	2017-11-30 16:41:12.387219535 +0500
@@ -318,7 +318,7 @@
 
   def self.latest_attach(attachments, filename)
     attachments.sort_by(&:created_on).reverse.detect do |att|
-      filename.casecmp(att.filename) == 0
+      filename.casecmp?(att.filename) == true
     end
   end