bug#64548: 29.0.92; Modus Themes Info manual is in "Unknown category"

[Stephen Berman]

After building Emacs from the release branch or from master, the
info/dir file looks like this (excerpted):

[...]
* Menu:

Texinfo documentation system
* Info: (info).                 How to use the documentation browsing system.

Emacs
* Emacs: (emacs).               The extensible self-documenting text editor.
* Emacs FAQ: (efaq).            Frequently Asked Questions about Emacs.

Emacs lisp
* Emacs Lisp Intro: (eintr).    A simple introduction to Emacs Lisp programming.
* Elisp: (elisp).               The Emacs Lisp Reference Manual.
[...]

Emacs misc features
* Autotype: (autotype).         Convenient features for text that you enter
                                  frequently in Emacs.
* Bovine: (bovine).             Semantic bovine parser development.
* Calc: (calc).                 Advanced desk calculator and mathematical tool.
* Dired-X: (dired-x).           Dired Extra Features.
[...]

Unknown category
*     Modus Themes: (modus-themes).      Elegant, highly legible and 
customizable themes.


The two odds things about the last entry are its category and the extra
space after the asterisk.  This odd category and appearance are only in
emacs-29 and master; in emacs-28 the Modus Themes manual is under the
"Emacs misc features" category and there's no extra space:


Emacs misc features
* Autotype: (autotype).         Convenient features for text that you enter
                                  frequently in Emacs.
* Bovine: (bovine).             Semantic bovine parser development.
* Calc: (calc).                 Advanced desk calculator and mathematical tool.
* Dired-X: (dired-x).           Dired Extra Features.
[...]
* Modus Themes: (modus-themes). Highly accessible themes (WCAG AAA).
* PCL-CVS: (pcl-cvs).           Emacs front-end to CVS.
[...]


I also checked the emacs-28.3-rc1.tar.xz and emacs-29.0.92.tar.xz
tarballs at alpha.gnu.org and the info/dir file in the latter tarball
has the same oddities with Modus Themes, while info/dir in the former
tarball does not.

I eyeballed doc/misc/modus-themes.texi, which is generated from
modus-themes.org, in emacs-29 and master, and the beginning of that file
appears similar to the start of other .texi files in that directory and
also to the start of org.texi, which is also generated (from org.org).
(One difference between modus-themes.org and org.org is that the latter
uses org-setup.org to generate the .texi file, while modus-themes.org
includes similar lines in the file itself instead of in a setup file.)
And the resulting modus-themes.info file also appears to be fine.
Moreover, when I execute `install-info ./modus-themes.info ./dir' from
the shell, using the modus-themes.info from the emacs-29 builds, the
resulting dir file contains the entry for Modus Themes under the "Emacs
misc features" category.  So it seems that problematic dir file results
from some other part of the build process, but I couldn't figure out
which.


In GNU Emacs 29.0.92 (build 1, x86_64-pc-linux-gnu, GTK+ Version
 3.24.38, cairo version 1.17.6) of 2023-07-02 built on strobelfssd
Repository revision: 37ed3d15f38339400eba67647c87fad85de3a384
Repository branch: emacs-29
Windowing system distributor 'The X.Org Foundation', version 11.0.12101008
System Description: Linux From Scratch r11.3-100-systemd

Configured using:
 'configure -C --with-xwidgets 'CFLAGS=-Og -g3'
 PKG_CONFIG_PATH=/opt/qt5/lib/pkgconfig'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
JSON LCMS2 LIBSYSTEMD LIBXML2 MODULES NOTIFY INOTIFY PDUMPER PNG RSVG
SECCOMP SOUND SQLITE3 THREADS TIFF TOOLKIT_SCROLL_BARS WEBP X11 XDBE XIM
XINPUT2 XPM XWIDGETS GTK3 ZLIB