Cannot reset the panels columns layout in the page administration to 'inherited' from higher level

How to reproduce:

• go to a page (any non terminal page)
• choose "administer page" from the menu
• go to the "Panels" section
• choose one of the page layouts by clicking one of the possible layouts:
  
• save
• exit the administration of the page and re-enter it, go to the panels administration

Expected result:

• there should be a way to unset the panels columns layout for this page, to make it inherit from the top level again

Actual result:

• there is no way to unset the panels columns, whatever choice is made at this level will be saved as an explicit choice at this level, and will not change along with a change at higher level.

There is a "reset" button in this UI but it does not seem to unset this choice, it seems to have as an effect that the list of panels is filled in, which is not what a reset would be expected to do.