The fix above will not work.
I can do it for "Prefer VC packages" only:
(require 'cl)
(defun package--get-activatable-pkg (pkg-name)
;; Is "activatable" a word?
(let ((pkg-descs
(flatten-list
(mapcar (lambda (x)
(sort x
(lambda (p1 p2)
(let ((v1 (package-desc-version p1))
(v2 (package-desc-version p2)))
(version-list-< v2 v1)))))
(reduce
(lambda (p1 p2)
(if (package-vc-p p1)
(push p1 (first p2))
(push p1 (second p2)))
p2)
(cdr (assq pkg-name package-alist))
:initial-value (list nil nil)
:from-end t)))))
;; Check if PACKAGE is available in `package-alist'.
(while
(when pkg-descs
(let ((available-version (package-desc-version (car pkg-descs))))
(package-disabled-p pkg-name available-version)))
(setq pkg-descs (cdr pkg-descs)))
(car pkg-descs)))
Still can't for "Prefer builtin packages".