Redmine

The change in #38772 prevents usage, if a class is a subclass of CustomField, e.g UserCustomField. No filter group name is used, because of this change. "Translation missing: de.field_cf_19" is used instead of the name of the custom field.

This patch solve this problem.

   def <=>(field)
-    return nil unless field.is_a?(CustomField)
+    return nil unless field.is_a?(self.class)

     position <=> field.position
   end

See https://www.redmine.org/projects/redmine/repository/svn/diff/trunk/app/models/custom_field.rb?utf8=%E2%9C%93&rev=22269&rev_to=22013