bug#37832: internal-border face ignored in Emacs 26.3 for macOS

[Andrea Cardaci]

The `internal-border` face is ignored and the `default` face
background is used instead. I'm experiencing this with Emacs 26.3
installed with `brew cask install emacs`.

Reproduce with the following `.emacs`:

(custom-set-variables
 '(default-frame-alist '((internal-border-width . 100))))

(custom-set-faces
 '(default ((t (:background "black" :foreground "white"))))
 '(internal-border ((t (:background "red")))))

Works fine on Linux version 26.1.


Andrea