I have no idea what's going on here, but it may be related to something
else I recently noticed.  My installed dir file in /usr/local/share/info
contains lots of lines like the following scattered throughout the file
(these lines are not in the dir file in the Emacs source directory):

This is ../../info/eintr, produced by makeinfo version 4.11 from emacs-lisp-intro.texi.

This is ../../info/sasl, produced by makeinfo version 4.11 from sasl.texi.

This is ../../info/remember, produced by makeinfo version 4.11 from remember.texi.

I don't know when these lines appeared, but I think it wasn't too long
ago.  Does anyone know what caused this?  FWIW, the Makefile installs
the Emacs Info files and dir in /usr/local/share/info, and I symlink
these to /usr/local/info, but I've been doing that for a long time and
I'm pretty sure the above lines are of more recent vintage.