Does not work with multiple submit buttons on a form

For example, of the Commerce 'cart' form, there are 2 submit buttons 'Update cart' and 'Checkout'.

If you click 'Checkout' (2nd submit button) the backend treats it like you clicked the 1st button (Update cart).

This is due to how the submit input elements are rendered.

I've changed the input--submit.html.twig to look like this instead to get it to work:

{{ attributes.value|render }}

I'll try and submit a patch if i get a little extra time.

But as you can see, the input should be outside of the , not inside it.