Fixed bug: Attachment import RecordNotUnique exception handling fails sometimes.

lib/import/otrs.rb

@@ -592,6 +592,10 @@ module Import::OTRS
       }
 
       record['Articles'].each do |article|
+
+        retries = 3
+        begin
+
           ActiveRecord::Base.transaction do
 
             # get article values
@@ -678,7 +682,6 @@ module Import::OTRS
 
               filename = Base64.decode64(attachment['Filename'])
 
-            begin
               Store.add(
                 object:      'Ticket::Article',
                 o_id:        article_object.id,
@@ -691,12 +694,14 @@ module Import::OTRS
                 },
                 created_by_id: 1,
               )
-            rescue ActiveRecord::RecordNotUnique
-              log "Ticket #{ticket_new[:id]} (article #{article_object.id}, filename #{filename}) is handled by another thead, skipping."
-              next
-            end
             }
           end
+        rescue ActiveRecord::RecordNotUnique => e
+          log "Ticket #{ticket_new[:id]} - RecordNotUnique: #{e}"
+          sleep rand 3
+          retry if !(retries -= 1).zero?
+          raise
+        end
       end
 
       #puts "HS: #{record['History'].inspect}"