Use Namespace.for_user scope (formerly known as Namespace.root)

app/models/namespace.rb

@@ -46,7 +46,7 @@ class Namespace < ActiveRecord::Base
   before_destroy(prepend: true) { prepare_for_destroy }
   after_destroy :rm_dir
-  scope :root, -> { where('type IS NULL') }
+  scope :for_user, -> { where('type IS NULL') }
   scope :with_statistics, -> do
     joins('LEFT JOIN project_statistics ps ON ps.namespace_id = namespaces.id')

app/models/user.rb

@@ -350,10 +350,8 @@ class User < ActiveRecord::Base
     end
     def find_by_full_path(path, follow_redirects: false)
-      namespace = Namespace.find_by_full_path(path, follow_redirects: follow_redirects)
-      return unless namespace && namespace.kind == 'user'
-
-      namespace.owner
+      namespace = Namespace.for_user.find_by_full_path(path, follow_redirects: follow_redirects)
+      namespace&.owner
     end
     def reference_prefix