Twenty Seventeen: Pre-sized Header Media not used

[madriverweb]

Theme: Twenty Seventeen
Version: current

The theme customizer has an option to add Header Media and recommends dimensions of 2000 x 1200 pixels. When images are uploaded, WordPress automatically creates a size 2000 x 1200 pixel.

The bug
When adding a new header image in the customizer, sizing of the original is still required, i.e. it does not automatically choose the pre-sized 2000 x 1200 image.

Steps to replicate:

1. Upload an image. Login to your FTP space and you will see a file sized to 2000 x 1200.
2. Go into customizer, Header Media, Add new image, select the one you just uploaded. Note that it will require you to size it to 2000 x 1200.