Import or clone of panel results in Fatal error (panels_display::set_state()

Just a note about how to resolve a panels issue with a fatal error on import. I believe this is a result of this panel having lived through Panels 2 and on into Panels 3, but tried to clone it today (or export and import, with same result)

Fatal error: Call to undefined method panels_display::__set_state() in /home/rfay/workspace/itsmylocker/sites/all/modules/contrib/ctools/page_manager/plugins/tasks/page.admin.inc(1263) : eval()'d code on line 26

It's not hard to fix: export the panel and in the exported code, change $page->conf - just delete it and put

$page->conf = array();