Bug#48717: simple config file merge option

[rossen@freesurf.ch]

<prod/><prod/><prod/>

For the Nth time today, I was presented with a choice like the
following:

Configuration file `/etc/Muttprintrc'
 ==> File on system created by you or by a script.
 ==> File also in package provided by package maintainer.
   What would you like to do about it ?  Your options are:
    Y or I  : install the package maintainer's version
    N or O  : keep your currently-installed version
      D     : show the differences between the versions
      Z     : background this process to examine the situation
 The default action is to keep your current version.
*** Muttprintrc (Y/I/N/O/D/Z) [default=N] ? i
Installing new version of config file /etc/Muttprintrc ...

Normally I would have ignored this and just done what I always do (i.e.
check the differences, and if the maintainer's version looked like a
significant improvement, install that and go back later to add my
changes, otherwise keep my version), but last night I was at a demo of
FreeBSD.  The administration functions of FreeBSD are sometimes
shockingly similar to Debian, including the upgrading of package
configuration files EXCEPT that they have a nice, convieniently-placed
option to merge differences interactively.

Would it be too much to ask for an option

      M     : merge differences interactively

and the related option (if M is called)

      C     : install custom-merged version

at this point and just call sdiff and let admins pick blocks of
differences manually?  I know that it is not as wonderfully automatic as
using a three-way merge, but it should be simple to implement.  This
wishlist item has been hanging around for more than two years now.

P.S. You might want to merge this wishlist item with #120152, since they
seem to be pratically identical.

-- 
Erik Rossen                         ^    OpenPGP key: 2935D0B9
rossen@freesurf.ch                 /e\   "Use GnuPG, see the
http://www.multimania.com/rossen   ---    black helicopters."