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 ?