Attached is a patch to automatically load custom-file when defined.

Motivation:
After 30 years of emacs use, I'm getting tired of the need to load
custom-file when you setq it.
And when introducing people to emacs, the question of why you need to load
it explicitly arises only too often.

Rationale:
1. if custom-file is nil, nothing changes
2. if you set custom-file:
  2a. If you don't load it explicitly in your init.el, it gets loaded at a
predictable place in the loading sequence (ie. after init.el was loaded)
  2b. If you load it explicity in init.el, it doesn't get loaded twice and
init.el "wins".
3. CORNER CASE:
   Q:Currently, my init.el defines custom-file, but I don't load it.
    A Add
  (setq custom-file-load-p nil)
to your init.el and emacs will not load custom-file

Best,
/Pedro A.Aranda
-- 
Fragen sind nicht da um beantwortet zu werden,
Fragen sind da um gestellt zu werden
Georg Kreisler