React Beautiful DnD example "resets" focus after drop

React Beautiful DnD example linked in the readme has a bug/nit:

* add 2 customers
* focus in c1 (top) last name
* start typing
* drag customer to reorder
* continue typing

If done slowly, 2nd run of typing will end up in c2 (new top) customer last name.

If done quickly, part of 2nd run of typing will be in c1 and part in c2.

It's also possible to type while dragging, which illustrates the issue better.

Start with the React Beautiful DnD example linked from the README and reproduce the reported sequence with two customers, typing while dragging and after reordering. Trace how focus changes during the drop; done means continued typing stays in the intended customer's last-name field instead of moving between customers.

Written by the indexing model from the issue text.