bug#31558: 27.0; `custom-file' settings messed up by Emacs 27

[Drew Adams <drew.adams@oracle.com>]

> > (defcustom tramp-verbose 3
> >   "..."
> >   :group 'tramp
> >   :type 'integer
> >   :set (lambda (sym val)
> >          (when (require 'tramp nil t)
> >            (custom-set-default sym val)))
> >   :initialize 'custom-initialize-set)
> 
> This results in
> 
> Loading tramp...
> Recursive load: "/net/ford/albinus/src/tramp/lisp/tramp.elc",
> "/net/ford/albinus/src/tramp/lisp/tramp.elc",
> "/net/ford/albinus/src/tramp/lisp/tramp.elc",
> "/net/ford/albinus/src/tramp/lisp/tramp.elc",
> "/net/ford/albinus/src/tramp/lisp/tramp.elc"

Hm, indeed.  Maybe :intialize needs to not try to set it here
(i.e., during loading).

Maybe :initialize needs to test (featurep 'tramp) or something?

Or maybe some other value of :initialize is appropriate?
`custom-initialize-default'? 
`custom-initialize-safe-set'?
`custom-initialize-safe-default'?

Dunno.  I'm no expert on loading and defcustom initialization.

> Well, maybe I try something like this next days, as time permits. And
> I'm always willing to test your proposals.

Thanks for taking a look at this.