Grammar error on authentication popup

[brenjt]

Expected result

1. The text in the authentication popup should say Checkout as a new customer

Actual result

1. Text current says: Checkout out as a new customer

[magento-team]

Internal ticket to track issue progress: MAGETWO-71833

[magento-engcom-team]

@brenjt thank you for your report.
The fix for this issue is already available in the develop branch. See PR #9533.

[purpletreesoft]

When is it going to be GA? well this was irritating for me so I ended up doing some work to fix it. See https://github.com/purpletreesoft/magento-checkout-fix