bug#12797: 24.3.50; mml-atttach-file (C-c C-a) and ido

[Jambunathan K]

When I am attaching files to mails via C-c C-a, I am fooled in to
thinking that the intereface for reading file is not that of ido but the
default one (Emacs + icomplete).  The problem is slightly exacerbated on
my end because of my patch to icomplete.el which shifts the field
separator from "," to " | ".  

I frequently type backspace at the prompt only to be disappointed that
the prompt doesn't back out to parent directory but only deletes a char.

1. I can defalias it

    (defalias 'read-file-name 'ido-read-file-name)

2. One can mark it separately thus (as ido already does for some
   functions)

    (put 'read-file-name 'ido 'ido-read-file-name)

I am not sure which of the options is best.  (2) might be better of the
two options but it needs extra handling elswhere.

Can someone install the needful, so that I don't keep tripping over
differences in the implementation.

In GNU Emacs 24.3.50.4 (i686-pc-linux-gnu, X toolkit, Xaw3d scroll bars)
 of 2012-11-03 on debian-6.05
Bzr revision: 110779 dmantipov@yandex.ru-20121103055917-30uwiia169kunlk2
Windowing system distributor `The X.Org Foundation', version 11.0.10707000
Important settings:
  value of $LANG: en_IN
  locale-coding-system: iso-latin-1-unix
  default enable-multibyte-characters: t