Since Emacs 25.1, package-list-packages modifies and writes my .emacs

Question

I've just installed Emacs 25.1. My .emacs works well on Emacs 24.5. But now that I'm on Emacs 25.1, when I do M-x package-list-packages, Emacs modifies and write .emacs in the background with the following modifications in custom-set-variables and custom-set-faces :

(custom-set-variables
 '(package-selected-packages
   (quote
    (yaml-mode w3m toml-mode thing-cmds slime-company rust-mode revive proc-net paredit monky minibuf-isearch markdown-mode magit list-processes+ imenu-list google-this ggtags expand-region emacs-cl elnode elisp-slime-nav company-c-headers common-lisp-snippets column-enforce-mode cl-generic cl-format aggressive-indent))))

and that :

(custom-set-faces
 '(default ((t (:height 110 :family "Monospace")))))

How can I prevent Emacs doing this ?

Answer 1

I've managed to prevent Emacs from modifying and writing my .emacs by setting the package-selected-packages to my list of packages I want to have installed by default.

For example, I have this configuration now:

(require 'package)
(add-to-list 'package-archives
             '("melpa" . "https://melpa.org/packages/"))
(add-to-list 'package-archives
         '("marmalade" .
           "https://marmalade-repo.org/packages/"))

(package-initialize)

(setq package-selected-packages
      '(
    aggressive-indent
    column-enforce-mode
    common-lisp-snippets
    company
    company-c-headers
    elisp-slime-nav
    expand-region
    ggtags
    google-this
    imenu-list
    macrostep
    magit
    markdown-mode
    monky
    paredit
    slime
    slime-company
    yaml-mode
    yasnippet
    ))

(defun install-packages ()
  "Install all required packages."
  (interactive)
  (unless package-archive-contents
    (package-refresh-contents))
  (dolist (package package-selected-packages)
    (unless (package-installed-p package)
      (package-install package))))

(install-packages)