M-x customize and long lines

[Yegor Timoshenko <yegortimoshenko@gmail.com>]

M-x customize sometimes produces very long lines (for example, try
customizing eshell-modules-list). Here's what I get:

(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.
 '(eshell-modules-list
   (quote
    (eshell-alias eshell-cmpl eshell-dirs eshell-glob eshell-hist eshell-ls
eshell-term eshell-tramp eshell-unix)))

How do I make M-x customize respect 80 chars per line limit? Is there a
hook? I couldn't find one.

Thanks!
Yegor