modify the code to solve the undefined problem in issue.rb

app/models/issue.rb

@@ -645,7 +645,7 @@ class Issue < ActiveRecord::Base
 
     user_real = user || User.current
     roles = user_real.admin ? Role.all : user_real.roles_for_project(project)
-    return {} if roles.empty?
+    return {} if roles.length == 0
 
     result = {}
     workflow_permissions = WorkflowPermission.where(:tracker_id => tracker_id, :old_status_id => status_id, :role_id => roles.map(&:id)).all