Merge branch 'rails5-mysql-rename-column' into 'master'

Rails5 MySQL fix rename_column as part of cleanup_concurrent_column_type_change for timestamps

See merge request gitlab-org/gitlab-ce!20514

changelogs/unreleased/rails5-mysql-rename-column.yml

+---
+title: Rails5 MySQL fix rename_column as part of cleanup_concurrent_column_type_change
+merge_request: 20514
+author: Jasper Maes
+type: fixed

config/initializers/active_record_table_definition.rb

@@ -29,6 +29,11 @@ module ActiveRecord
       def datetime_with_timezone(column_name, **options)
         column(column_name, :datetime_with_timezone, options)
       end
+
+      # Disable timestamp alias to datetime
+      def aliased_types(name, fallback)
+        fallback
+      end
     end
   end
 end