Replying to designsimply:
I also tested 32672.2.diff, but I spotted an error in the console and the first menu gets listed twice in the Menu Locations panel if you follow the testing steps exactly and click Save & Publish before going to Menu Locations (screenshot).
@gabrielperezs and I took a look at this during WCEU's contributor day. Both patches apply without issue, but introduce a new bug with the Menu Locations.
We were not able to reproduce the duplicate menus in the Locations Panel, but we are noticing that the newly created menus will not appear in the Locations Panel, without a Save & Publish action. Otherwise, the menu remains empty.
Steps to reproduce.
1.) Apply 32672.2.diff
2.) Add a new menu via the Customizer's Menu Panel.
3.) Select a menu location from the Menu Panel.
4.) Without saving, navigate to the Menu Locations Panel.
The newly created menu will not appear, presumably because the newly created menu is never saved.
We are only seeing this behavior in twentyfifteen and twentyeleven.