"Select" control in the Customizer doesn't work since WP 4.9 Beta 3

[bduclos]

Since Beta 3, the "select" control doesn't work, it appears empty.
e.g. if the theme supports "custom-background", the Preset and Image Size "select" controls appear empty:

Also some Custom Controls don't work anymore and display an empty input.
e.g. if you activate the "Storefront" theme, they have a "More" section which now displays an empty input instead of their text.

[westonruter]

Thanks for reporting. This was reported and fixed last night in #42286 via [41952].

Please update to a nightly to confirm the fix. This will be part of 4.9-beta4.