Merge branch 'pages-api-lowercase-namespaces' into 'master'

Fix finding namespace with mixed case saved path

See merge request gitlab-org/gitlab!27566

app/models/namespace.rb

@@ -130,7 +130,7 @@ class Namespace < ApplicationRecord
       return unless host.ends_with?(gitlab_host)
 
       name = host.delete_suffix(gitlab_host)
-      Namespace.where(parent_id: nil).find_by_path(name)
+      Namespace.where(parent_id: nil).by_path(name)
     end
 
     # overridden in ee

spec/models/namespace_spec.rb

@@ -194,7 +194,7 @@ describe Namespace do
 
   describe '.find_by_pages_host' do
     it 'finds namespace by GitLab Pages host and is case-insensitive' do
-      namespace = create(:namespace, name: 'topnamespace')
+      namespace = create(:namespace, name: 'topNAMEspace', path: 'topNAMEspace')
       create(:namespace, name: 'annother_namespace')
       host = "TopNamespace.#{Settings.pages.host.upcase}"