Emacs inserts hardwired org-agenda-files variable, overwriting user options

[daniela-spit]

I have identified a problem. Let a user set the files to be used for
Org Agenda in .emacs as follows, and consider the situation when the
file writing.rcl.org does not exist.

(setq org-agenda-files
   '("~/02histr/gadmin/writing.rcl.org"
     "~/02histr/gadmin/meeting.rcl.org"
     "~/02histr/gadmin/household.rcl.org"))

Emacs demands that the file writing.rcl.org be removed from org-agenda-files.
Then Emacs sabotages the user's settings by hardwiring org-agenda-files at the
end of the file .emacs by inserting:

(custom-set-variables
;; custom-set-variables was added by Custom.
;; If you edit it by hand, you could mess it up, so be careful.
;; Your init file should contain only one such instance.
;; If there is more than one, they won't work right.
'(org-agenda-files
    '("~/02histr/gadmin/meeting.rcl.org" "~/02histr/gadmin/household.rcl.org")))

This should be considered a bug.