Description

Currently, it's not possible to assign menu locations to a different menu using the "Manage Locations" modal.

Step-by-step reproduction instructions

Tested using TT1 theme.

1. Go to the experimental Navigation screen.
2. Create two menus.
3. Assign both locations to the first menu.
4. Open the "Manage Locations" modal.
5. Assing both locations to the second menu.
6. Save menu and refresh page.
7. Locations aren't reassigned.

Expected Behavior

The editor shouldn't assign menu locations to the second menu.

Current Behavior

The editor doesn't assign menu locations to the second menu.

Screenshots or screen recording (optional)