blur is prevented when dragging a sortable-item

When you drag a sortable-item, if there was a previous focused element, it never loses focus.

I made a twiddle to reproduce the issue:
https://ember-twiddle.com/71480160a6682f5d9191f2a70c1b5d8e?openFiles=templates.application.hbs%2C

Basically if you focus the input and then reorder one of the items, you can notice that the input stays focused.