bug#7942: 23.2; Duplicate entries in Info dir file

[Chong Yidong]

Eli Zaretskii <eliz@gnu.org> writes:

>> I think we should change our dir file so that it matches the dircategory
>> tags in the manual files.
>
> I think we should fix it the other way around: make the dircategory in
> the manual files match what we want to see in `dir'.

It's not so simple.

If someone has dirfile entries from a previous installation of Emacs,
and then installs Emacs 23.3, new directory entries for the 23.3 manuals
would be installed into the dirfile, under the "new" categories.  But
the old directory entries would not be removed.

The Emacs Info reader (not sure about the standalone reader), when
rendering the dirfile, then removes the duplicate entries---so
everything gets lumped under "Emacs" anyway.