Steps to reproduce the issue

• Create a custom field.
• Create a subform with the created custom field.
• Save the subform.
• Try to change the selected field in the subform.
• Select the current subform from the list.
• Try to create a new article.

Expected result

The subform you are in should not be in the list.

Actual result

The subform you are in is in the select list.

This breaks the edit view of the place this subform is included in.

System information (as much as possible)

Additional comments

Problem is in 5.3 and newer.