e group...
					foreach ( $slug_group as $slug ) {

						// ... have a match as well.
						if ( is_string( $location ) && false === stripos( $location, $slug ) && false === stripos( $slug, $location ) ) {
							continue;
						} elseif ( is_numeric( $location ) && $location !== $slug ) {
							continue;
						}

						// Make sure this location wasn't mapped and removed previously.
						if ( ! empty( $old_nav_menu_locations[ $location ] ) ) {

							// We have a match that can be mapped!
							$new_nav_menu_locations[ $new_location ] = $old_nav_menu_locations[ $location ];

							// Remove the mapped location so it can't be mapped again.
							unset( $old_nav_menu_locations[ $location ] );

							// Go back and check the next new menu location.
							continue 3;
						}
					} // End foreach ( $slug_group as $slug ).
				} // End foreach ( $old_nav_menu_locations as $location => $menu_id ).
			} // End foreach foreach ( $registered_nav_menus as $new_location => $name ).
		} // End foreach ( $slug_group as $slug ).
	} // End foreach ( $common_slug_groups as $slug_group ).

	return $new_nav_menu_locations;
}