[mew-int 3141] mew-attach-duplicate binds completion-ignored-extensions to nil

Why does mew-attach-duplicate bind completion-ignored-extensions to nil?
This overrides a user's preferences as to which files to present when doing
completion.

(It also triggers a bug in Ubuntu's version of the w3m-el package.  w3m-el
includes an old version of regexp-opt.el that suffers an infinite recursion
when executing (regexp-opt nil).  I can work around that by running "sudo
apt-get remove w3m-el".)

		    -Mike